如何系统地自学 Swift 语言并学会 iOS 开发？

var v1:String = "hi" // 标注类型
var v2 = "类型推导"
let l1 = "标题" // 常量
class a {
    let p1 = 3
    var p2: Int {
        p1 * 3
}

print("hi")
let i = 14
print(i)
print("9月\(i)是小柠檬的生日")
for i in 1...3{
    print(i)
// output:
// 使用terminator使循环打印更整洁
for i in 1...3 {
    print("\(i) ", terminator: "")
// output:
// 1 2 3

// 单行注释
多行注释第一行。
多行注释第二行。
// MARK: 会在 minimap 上展示
// TODO: 待做
// FIXME: 待修复

var o: Int? = nil
let i = o ?? 0

let a1 = [1,3,2].sorted(by: { (l: Int, r: Int) -> Bool in
    return l < r
// 如果闭包是唯一的参数并在表达式最后可以使用结尾闭包语法，写法简化为
let a2 = [1,3,2].sorted { (l: Int, r: Int) -> Bool in
    return l < r
// 已知类型可以省略
let a3 = [1,3,2].sorted { l, r in
    return l < r
// 通过位置来使用闭包的参数，最后简化如下：
let a4 = [1,3,2].sorted { $0 < $1 }

// 为参数设置默认值
func f1(p: String = "p") -> String {
    "p is \(p)"
// 函数作为参数
func f2(fn: (String) -> String, p: String) -> String {
    return fn(p)
print(f2(fn:f1, p: "d")) // p is d
// 函数作为返回值
func f3(p: String) -> (String) -> String {
    return f1
print(f3(p: "yes")("no")) // p is no

func f4(s: String..., i: Int...) {
    print(s)
    print(i)
f4(s: "one", "two", "three", i: 1, 2, 3)
/// ["one", "two", "three"]
/// [1, 2, 3]

func f5() {
    nf5()
    func nf5() {
        print("this is nested function")
f5() // this is nested function

// Int
let i1 = 100
let i2 = 22
print(i1 / i2) // 向下取整得 4
// Float
let f1: Float = 100.0
let f2: Float = 22.0
print(f1 / f2) // 4.5454545
let f3: Float16 = 5.0 // macOS 还不能用
let f4: Float32 = 5.0
let f5: Float64 = 5.0
let f6: Float80 = 5.0
print(f4, f5, f6) // 5.0 5.0 5.0
// Double
let d1: Double = 100.0
let d2: Double = 22.0
print(d1 / d2) // 4.545454545454546
// 字面量
print(Int(0b10101)) // 0b 开头是二进制 
print(Int(0x00afff)) // 0x 开头是十六进制
print(2.5e4) // 2.5x10^4 十进制用 e
print(0xAp2) // 10*2^2  十六进制用 p
print(2_000_000) // 2000000
// isMultiple(of:) 方法检查一个数字是否是另一个数字的倍数
let i3 = 36
print(i3.isMultiple(of: 9)) // true

var b = false
b.toggle() // true
b.toggle() // false

let t1 = (p1: 1, p2: "two", p3: [1,2,3])
print(t1.p1)
print(t1.p3)
// 类型推导
let t2 = (1, "two", [1,2,3])
// 通过下标访问
print(t2.1) // two
// 分解元组
let (dp1, dp2, _) = t2
print(dp1)
print(dp2)

let s1 = "Hi! This is a string. Cool?"
/// 转义符 \n 表示换行。
/// 其它转义字符有 \0 空字符)、\t 水平制表符 、\n 换行符、\r 回车符
let s2 = "Hi!\nThis is a string. Cool?"
// 多行
let s3 = """
This is a string.
Cool?
// 长度
print(s3.count)
print(s3.isEmpty)
// 拼接
print(s3 + "\nSure!")
// 字符串中插入变量
let i = 1
print("Today is good day, double \(i)\(i)!")
/// 遍历字符串
/// 输出：
/// o
/// n
/// e
for c in "one" {
    print(c)
// 查找
print(s3.lowercased().contains("cool")) // true
// 替换
let s4 = "one is two"
let newS4 = s4.replacingOccurrences(of: "two", with: "one")
print(newS4)
// 删除空格和换行
let s5 = " Simple line. \n\n  "
print(s5.trimmingCharacters(in: .whitespacesAndNewlines))
// 切割成数组
let s6 = "one/two/three"
let a1 = s6.components(separatedBy: "/") // 继承自 NSString 的接口
print(a1) // ["one", "two", "three"]
let a2 = s6.split(separator: "/")
print(a2) // ["one", "two", "three"] 属于切片，性能较 components 更好
// 判断是否是某种类型
let c1: Character = " "
print(c1.isASCII) // false
print(c1.isSymbol) // true
print(c1.isLetter) // false
print(c1.isNumber) // false
print(c1.isUppercase) // false
// 字符串和 Data 互转
let data = Data("hi".utf8)
let s7 = String(decoding: data, as: UTF8.self)
print(s7) // hi
// 字符串可以当作集合来用。
let revered = s7.reversed()
print(String(revered))

// 原始字符串在字符串前加上一个或多个#符号。里面的双引号和转义符号将不再起作用了，如果想让转义符起作用，需要在转义符后面加上#符号。
let s8 = #"\(s7)\#(s7) "one" and "two"\n. \#nThe second line."#
print(s8)
/// \(s7)hi "one" and "two"\n.
/// The second line.
// 原始字符串在正则使用效果更佳，反斜杠更少了。
let s9 = "\\\\[A-Z]+[A-Za-z]+\\.[a-z]+"
let s10 = #"\\[A-Z]+[A-Za-z]+\.[a-z]+"#
print(s9) // \\[A-Z]+[A-Za-z]+\.[a-z]+
print(s10) // \\[A-Z]+[A-Za-z]+\.[a-z]+

enum E1:String, CaseIterable {
    case e1, e2 = "12"
// 关联值
enum E2 {
    case e1([String])
    case e2(Int)
let e1 = E2.e1(["one","two"])
let e2 = E2.e2(3)
switch e1 {
case .e1(let array):
    print(array)
case .e2(let int):
    print(int)
print(e2)
// 原始值
print(E1.e1.rawValue)
// 遵循 CaseIterable 协议可迭代
for ie in E1.allCases {
    print("show \(ie)")
// 递归枚举
enum RE {
    case v(String)
    indirect case node(l:RE, r:RE)
let lNode = RE.v("left")
let rNode = RE.v("right")
let pNode = RE.node(l: lNode, r: rNode)
switch pNode {
case .v(let string):
    print(string)
case .node(let l, let r):
    print(l,r)
    switch l {
    case .v(let string):
        print(string)
    case .node(let l, let r):
        print(l, r)
    switch r {
    case .v(let string):
        print(string)
    case .node(let l, let r):
        print(l, r)
}

// @unknown
enum E3 {
    case e1, e2, e3
func fe1(e: E3) {
    switch e {
    case .e1:
        print("e1 ok")
    case .e2:
        print("e2 ok")
    case .e3:
        print("e3 ok")
    @unknown default:
        print("not ok")
}

// Comparable 枚举比较
enum E4: Comparable {
    case e1, e2
    case e3(i: Int)
    case e4
let e3 = E4.e4
let e4 = E4.e3(i: 3)
let e5 = E4.e3(i: 2)
let e6 = E4.e1
print(e3 > e4) // true
let a1 = [e3, e4, e5, e6]
let a2 = a1.sorted()
for i in a2 {
    print(i.self)
/// e1
/// e3(i: 2)
/// e3(i: 3)
/// e4

func fn<T>(p: T) -> [T] {
    var r = [T]()
    r.append(p)
    return r
print(fn(p: "one"))
// 结构体
struct S1<T> {
    var arr = [T]()
    mutating func add(_ p: T) {
        arr.append(p)
var s1 = S1(arr: ["zero"])
s1.add("one")
s1.add("two")
print(s1.arr) // ["zero", "one", "two"]

protocol pc {
    associatedtype T
    mutating func add(_ p: T)
struct S2: pc {
    typealias T = String // 类型推导，可省略
    var strs = [String]()
    mutating func add(_ p: String) {
        strs.append(p)
}

struct S3<T> {
    struct S4 {
        var p: T
    var p1: T
    var p2: S4
let s2 = S3(p1: 1, p2: S3.S4(p: 3))
let s3 = S3(p1: "one", p2: S3.S4(p: "three"))
print(s2,s3)

protocol P {
    func f() -> String
struct S1: P {
    func f() -> String {
        return "one\n"
struct S2<T: P>: P {
    var p: T
    func f() -> String {
        return p.f() + "two\n"
struct S3<T1: P, T2: P>: P {
    var p1: T1
    var p2: T2
    func f() -> String {
        return p1.f() + p2.f() + "three\n"
func someP() -> some P {
    return S3(p1: S1(), p2: S2(p: S1()))
let r = someP()
print(r.f())

extension URLSession {
    func dataTaskWithResult(
        with url: URL,
        handler: @escaping (Result<Data, Error>) -> Void
    ) -> URLSessionDataTask {
        dataTask(with: url) { data, _, err in
            if let err = err {
                handler(.failure(err))
            } else {
                handler(.success(data ?? Data()))
let url = URL(string: "https://ming1016.github.io/")!
// 以前网络请求
let t1 = URLSession.shared.dataTask(with: url) {
    data, _, error in
    if let err = error {
        print(err)
    } else if let data = data {
        print(String(decoding: data, as: UTF8.self))
t1.resume()
// 使用 Result 网络请求
let t2 = URLSession.shared.dataTaskWithResult(with: url) { result in
    switch result {
    case .success(let data):
        print(String(decoding: data, as: UTF8.self))
    case .failure(let err):
        print(err)
t2.resume()

class S0 {}
class S1: S0 {}
class S2: S0 {}
var a = [S0]()
a.append(S1())
a.append(S2())
for e in a {
    // 类型判断
    if e is S1 {
        print("Type is S1")
    } else if e is S2 {
        print("Type is S2")
    // 使用 as 关键字转换成子类
    if let s1 = e as? S1 {
        print("As S1 \(s1)")
    } else if let s2 = e as? S2 {
        print("As S2 \(s2)")
}

class C {
     var p: String
     init(_ p: String) {
         self.p = p
     // 下标操作
     subscript(s: String) -> String {
         get {
             return p + s
         set {
             p = s + newValue
 let c = C("hi")
 print(c.p)
 print(c[" ming"])
 c["k"] = "v"
 print(c.p)

struct S {
    var p1: String = ""
    var p2: Int
extension S {
    func f() -> String {
        return p1 + String(p2)
var s = S(p2: 1)
s.p1 = "1"
print(s.f()) // 11

struct S {
    static let sp = "类型属性" // 类型属性通过类型本身访问，非实例访问
    var p1: String = ""
    var p2: Int = 1
    // cp 是计算属性
    var cp: Int {
        get {
            return p2 * 2
        set {
            p2 = newValue + 2
    // 只有 getter 的是只读计算属性
    var rcp: Int {
        p2 * 4
print(S.sp)
print(S().cp) // 2
var s = S()
s.cp = 3
print(s.p2) // 5
print(S().rcp) // 4

struct S2 {
    let p1: String
    let p2: Int
let s2 = S2(p1: "one", p2: 1)
let s3 = S2(p1: "two", p2: 2)
let a1 = [s2, s3]
let a2 = a1.map(\.p1)
print(a2) // ["one", "two"]

enum E: String {
    case one, two, three
    func showRawValue() {
        print(rawValue)
let e = E.three
e.showRawValue() // three
// 可变的实例方法，使用 mutating 标记
struct S {
    var p: String
    mutating func addFullStopForP() {
        p += "."
var s = S(p: "hi")
s.addFullStopForP()
print(s.p)
// 类方法
class C {
    class func cf() {
        print("类方法")
}

// 静态下标
struct S2 {
    static var sp = [String: Int]()
    static subscript(_ s: String, d: Int = 10) -> Int {
        get {
            return sp[s] ?? d
        set {
            sp[s] = newValue
S2["key1"] = 1
S2["key2"] = 2
print(S2["key2"]) // 2
print(S2["key3"]) // 10

// callAsFunction()
struct S3 {
    var p1: String
    func callAsFunction() -> String {
        return "show \(p1)"
let s2 = S3(p1: "hi")
print(s2()) // show hi

// 类继承
class C1 {
    var p1: String
    var cp1: String {
        get {
            return p1 + " like ATM"
        set {
            p1 = p1 + newValue
    init(p1: String) {
        self.p1 = p1
    func sayHi() {
        print("Hi! \(p1)")
class C2: C1 {
    var p2: String
    init(p2: String) {
        self.p2 = p2
        super.init(p1: p2 + "'s father")
C2(p2: "Lemon").sayHi() // Hi! Lemon's father
// 重写父类方法
class C3: C2 {
    override func sayHi() {
        print("Hi! \(p2)")
C3(p2: "Lemon").sayHi() // Hi! Lemon
// 重写计算属性
class C4: C1 {
    override var cp1: String {
        get {
            return p1 + " like Out of the blade"
        set {
            p1 = p1 + newValue
print(C1(p1: "Lemon").cp1) // Lemon like ATM
print(C4(p1: "Lemon").cp1) // Lemon like Out of the blade

let a1 = ["a", "b", "c"]
let a2 = a1.map {
    "\($0)2"
print(a2) // ["a2", "b2", "c2"]

let a1 = ["a", "b", "c", "call my name"]
let a2 = a1.filter {
    $0.prefix(1) == "c"
print(a2) // ["c", "call my name"]

let a1 = ["a", "b", "c", "call my name.", "get it?"]
let a2 = a1.reduce("Hey u,", { partialResult, s in
    // partialResult 是前面返回的值，s 是遍历到当前的值
    partialResult + " \(s)"
print(a2) // Hey u, a b c call my name. get it?

// 类型遵循 Comparable
let a1 = ["a", "b", "c", "call my name.", "get it?"]
let a2 = a1.sorted()
let a3 = a1.sorted(by: >)
let a4 = a1.sorted(by: <)
print(a2) // Hey u, a b c call my name. get it?
print(a3) // ["get it?", "call my name.", "c", "b", "a"]
print(a4) // ["a", "b", "c", "call my name.", "get it?"]
// 类型不遵循 Comparable
struct S {
    var s: String
    var i: Int
let a5 = [S(s: "a", i: 0), S(s: "b", i: 1), S(s: "c", i: 2)]
let a6 = a5
    .sorted { l, r in
        l.i > r.i
    .map {
print(a6) // [2, 1, 0]

// if
let s = "hi"
if s.isEmpty {
    print("String is Empty")
} else {
    print("String is \(s)")
// 三元条件
s.isEmpty ? print("String is Empty again") : print("String is \(s) again")
// if let-else
func f(s: String?) {
    if let s1 = s {
        print("s1 is \(s1)")
    } else {
        print("s1 is nothing")
    // nil-coalescing
    let s2 = s ?? "nothing"
    print("s2 is \(s2)")
f(s: "something")
f(s: nil)
// if case let
enum E {
    case c1(String)
    case c2([String])
    func des() {
        switch self {
        case .c1(let string):
            print(string)
        case .c2(let array):
            print(array)
E.c1("enum c1").des()
E.c2(["one", "two", "three"]).des()

// guard
func f1(p: String) -> String {
    guard p.isEmpty != true else {
        return "Empty string."
    return "String \(p) is not empty."
print(f1(p: "")) // Empty string.
print(f1(p: "lemon")) // String lemon is not empty.
// guard let
func f2(p1: String?) -> String {
    guard let p2 = p1 else {
        return "Nil."
    return "String \(p2) is not nil."
print(f2(p1: nil)) // Nil.
print(f2(p1: "lemon")) // String lemon is not nil.

let a = ["one", "two", "three"]
for str in a {
    print(str)
// 使用下标范围
for i in 0..<10 {
    print(i)
// 使用 enumerated
for (i, str) in a.enumerated() {
    print("第\(i + 1)个是:\(str)")
// for in where
for str in a where str.prefix(1) == "t" {
    print(str)
// 字典 for in，遍历是无序的
let dic = [
    "one": 1,
    "two": 2,
    "three": 3
for (k, v) in dic {
    print("key is \(k), value is \(v)")
// stride
for i in stride(from: 10, through: 0, by: -2) {
    print(i)
 */

// while
var i1 = 10
while i1 > 0 {
    print("positive even number \(i1)")
    i1 -= 2
// repeat while
var i2 = 10
repeat {
    print("positive even number \(i2)")
    i2 -= 2
} while i2 > 0

func f1(pa: String, t:(String, Int)) {
    var p1 = 0
    var p2 = 10
    switch pa {
    case "one":
        p1 = 1
    case "two":
        p1 = 2
        fallthrough // 继续到下个 case 中
    default:
        p2 = 0
    print("p1 is \(p1)")
    print("p2 is \(p2)")
    // 元组
    switch t {
    case ("0", 0):
        print("zero")
    case ("1", 1):
        print("one")
    default:
        print("no")
f1(pa: "two", t:("1", 1))
 p1 is 2
 p2 is 0
// 枚举
enum E {
    case one, two, three, unknown(String)
func f2(pa: E) {
    var p: String
    switch pa {
    case .one:
        p = "1"
    case .two:
        p = "2"
    case .three:
        p = "3"
    case let .unknown(u) where Int(u) ?? 0 > 0 : // 枚举关联值，使用 where 增加条件
        p = u
    case .unknown(_):
        p = "negative number"
    print(p)
f2(pa: E.one) // 1
f2(pa: E.unknown("10")) // 10
f2(pa: E.unknown("-10")) // negative number

var a0: [Int] = [1, 10]
a0.append(2)
a0.remove(at: 0)
print(a0) // [10, 2]
let a1 = ["one", "two", "three"]
let a2 = ["three", "four"]
// 找两个集合的不同
let dif = a1.difference(from: a2) // swift的 diffing 算法在这 http://www.xmailserver.org/diff2.pdf swift实现在  swift/stdlib/public/core/Diffing.swift
for c in dif {
    switch c {
    case .remove(let o, let e, let a):
        print("offset:\(o), element:\(e), associatedWith:\(String(describing: a))")
    case .insert(let o, let e, let a):
        print("offset:\(o), element:\(e), associatedWith:\(String(describing: a))")
 remove offset:1, element:four, associatedWith:nil
 insert offset:0, element:one, associatedWith:nil
 insert offset:1, element:two, associatedWith:nil
let a3 = a2.applying(dif) ?? [] // 可以用于添加删除动画
print(a3) // ["one", "two", "three"]

print(a0.randomElement() ?? 0)

// 排序
struct S1 {
    let n: Int
    var b = true
let a4 = [
    S1(n: 1),
    S1(n: 10),
    S1(n: 3),
    S1(n: 2)
let a5 = a4.sorted { i1, i2 in
    i1.n < i2.n
for n in a5 {
    print(n)
/// S1(n: 1)
/// S1(n: 2)
/// S1(n: 3)
/// S1(n: 10)
let a6 = [1,10,4,7,2]
print(a6.sorted(by: >)) // [10, 7, 4, 2, 1]

extension Array where Element == Int {
    // 升序
    func intSortedASC() -> [Int] {
        return self.sorted(by: <)
    // 降序
    func intSortedDESC() -> [Int] {
        return self.sorted(by: <)
print(a6.intSortedASC()) // 使用扩展增加自定义排序能力

// 第一个满足条件了就返回
let a7 = a4.first {
    $0.n == 10
print(a7?.n ?? 0)
// 是否都满足了条件
print(a4.allSatisfy { $0.n == 1 }) // false
print(a4.allSatisfy(\.b)) // true
// 找出最大的那个
print(a4.max(by: { e1, e2 in
    e1.n < e2.n
}) ?? S1(n: 0))
// S1(n: 10, b: true)
// 看看是否包含某个元素
print(a4.contains(where: {
    $0.n == 7
// false

// 切片
// 取前3个，并不是直接复制，对于大的数组有性能优势。
print(a6[..<3]) // [1, 10, 4] 需要做越界检查
print(a6.prefix(30)) // [1, 10, 4, 7, 2] 不需要做越界检查，也是切片，性能一样
// 去掉前3个
print(a6.dropFirst(3)) // [7, 2]

let a8 = [8, 9, 20, 1, 35, 3]
let a9 = a8.prefix {
    $0 < 30
print(a9) // [8, 9, 20, 1]
let a10 = a8.drop {
    $0 < 30
print(a10) // [35, 3]

// 删除所有不满足条件的元素
var a11 = [1, 3, 5, 12, 25]
a11.removeAll { $0 < 10 }
print(a11) // [4, 3, 1, 3, 3] 随机
// 创建未初始化的数组
let a12 = (0...4).map { _ in
    Int.random(in: 0...5)
print(a12) // [0, 3, 3, 2, 5] 随机

// #if 用于后缀表达式
let a13 = a11
#if os(iOS)
    .count
#else
    .reduce(0, +)
#endif
print(a13) //37

let s0: Set<Int> = [2, 4]
let s1: Set = [2, 10, 6, 4, 8]
let s2: Set = [7, 3, 5, 1, 9, 10]
let s3 = s1.union(s2) // 合集
let s4 = s1.intersection(s2) // 交集
let s5 = s1.subtracting(s2) // 非交集部分
let s6 = s1.symmetricDifference(s2) // 非交集的合集
print(s3) // [4, 2, 1, 7, 3, 10, 8, 9, 6, 5]
print(s4) // [10]
print(s5) // [8, 4, 2, 6]
print(s6) // [9, 1, 3, 4, 5, 2, 6, 8, 7]
// s0 是否被 s1 包含
print(s0.isSubset(of: s1)) // true
// s1 是否包含了 s0
print(s1.isSuperset(of: s0)) // true
let s7: Set = [3, 5]
// s0 和 s7 是否有交集
print(s0.isDisjoint(with: s7)) // true
// 可变 Set
var s8: Set = ["one", "two"]
s8.insert("three")
s8.remove("one")
print(s8) // ["two", "three"]

var d1 = [
    "k1": "v1",
    "k2": "v2"
d1["k3"] = "v3"
d1["k4"] = nil
print(d1) // ["k2": "v2", "k3": "v3", "k1": "v1"]
for (k, v) in d1 {
    print("key is \(k), value is \(v)")
 key is k1, value is v1
 key is k2, value is v2
 key is k3, value is v3
if d1.isEmpty == false {
    print(d1.count) // 3
// mapValues
let d2 = d1.mapValues {
    $0 + "_new"
print(d2) // ["k2": "v2_new", "k3": "v3_new", "k1": "v1_new"]
// 对字典的值或键进行分组
let d3 = Dictionary(grouping: d1.values) {
    $0.count
print(d3) // [2: ["v1", "v2", "v3"]]
// 从字典中取值，如果键对应无值，则使用通过 default 指定的默认值
d1["k5", default: "whatever"] += "."
print(d1["k5"] ?? "") // whatever.
let v1 = d1["k3", default: "whatever"]
print(v1) // v3
// compactMapValues() 对字典值进行转换和解包。可以解可选类型，并去掉 nil 值
let d4 = [
    "k1": 1,
    "k2": 2,
    "k3": nil
let d5 = d4.mapValues { $0 }
let d6 = d4.compactMapValues{ $0 }
print(d5)
// ["k3": nil, "k1": Optional(1), "k2": Optional(2)]
print(d6)
// ["k1": 1, "k2": 2]

let i1 = 1
var i2 = i1
i2 = 2
print(i2) // 2
i2 += 1
print(i2) // 3
i2 -= 2
print(i2) // 1
i2 *= 10
print(i2) // 10
i2 /= 2
print(i2) // 5

let i1 = 1
let i2 = i1
print((i1 + i2 - 1) * 10 / 2 % 3) // 2
print("i" + "1") // i1
// 一元运算符
print(-i1) // -1

print(1 > 2) // false
struct S: Equatable {
    var p1: String
    var p2: Int
let s1 = S(p1: "one", p2: 1)
let s2 = S(p1: "two", p2: 2)
let s3 = S(p1: "one", p2: 2)
let s4 = S(p1: "one", p2: 1)
print(s1 == s2) // false
print(s1 == s3) // false
print(s1 == s4) // true

class C: Equatable {
    var p1: String
    var p2: Int
    init(p1: String, p2: Int) {
        self.p1 = p1
        self.p2 = p2
    static func == (l: C, r: C) -> Bool {
        return l.p1 == r.p1 && l.p2 == r.p2
let c1 = C(p1: "one", p2: 1)
let c2 = C(p1: "one", p2: 1)
print(c1 == c2)
// 元组比较
// 会先比较第一个数，第一个无法比较才会比较第二个数
// 字符串比较和字母大小还有长度有关。先比较字母大小，在比较长度
("apple", 1) < ("apple", 2) // true
("applf", 1) < ("apple", 2) // false
("appl", 2) < ("apple", 1) // true
("appm", 2) < ("apple", 1) // false

// if else
func f1(p: Int) {
    if p > 0 {
        print("positive number")
    } else {
        print("negative number")
// 三元
func f2(p: Int) {
    p > 0 ? print("positive number") : print("negative number")
f1(p: 1)
f2(p: 1)

// if else
func f1(p: Int?) {
    if let i = p {
        print("p have value is \(i)")
    } else {
        print("p is nil, use defalut value")
// 使用 ??
func f2(p: Int?) {
    let i = p ?? 0
    print("p is \(i)")
}

// 封闭范围
for i in 0...10 {
    print(i)
// 半开范围
for i in 0..<10 {
    print(i)
// 单侧区间
let nums = [5,6,7,8]
print(nums[2...]) // 7 8

let i1 = -1
let i2 = 2
if i1 != i2 && (i1 < 0 || i2 < 0) {
    print("i1 and i2 not equal, and one of them is negative number.")
}

class C {
    var p: String
    init(p: String) {
        self.p = p
let c1 = C(p: "one")
let c2 = C(p: "one")
let c3 = c1
print(c1 === c2) // false
print(c1 === c3) // true
print(c1 !== c2) // true

let i1: UInt8 = 0b00001111
let i2 = ~i1 // Bitwise NOT Operator（按位取反运算符），取反
let i3: UInt8 = 0b00111111
let i4 = i1 & i3 // Bitwise AND Operator（按位与运算符），都为1才是1
let i5 = i1 | i3 // Bitwise OR Operator（按位或运算符），有一个1就是1
let i6 = i1 ^ i3 // Bitwise XOR Operator（按位异或运算符），不同为1，相同为0
print(i1,i2,i3,i4,i5,i6)
// << 按位左移，>> 按位右移
let i7 = i1 << 1
let i8 = i1 >> 2
print(i7,i8)

var i1 = Int.max
print(i1) // 9223372036854775807
i1 = i1 &+ 1
print(i1) // -9223372036854775808
i1 = i1 &+ 10
print(i1) // -9223372036854775798
var i2 = UInt.max
i2 = i2 &+ 1
print(i2) // 0

let now = Date()
// Date 转 时间戳
let interval = now.timeIntervalSince1970 // 时间戳
let df = DateFormatter()
df.dateFormat = "yyyy 年 MM 月 dd 日 HH:mm:ss"
print("时间戳：\(Int(interval))") // 时间戳：1642399901
print("格式化的时间：" + df.string(from: now)) // 格式化的时间：2022 年 01 月 17 日 14:11:41
df.dateStyle = .short
print("short 样式时间：" + df.string(from: now)) // short 样式时间：2022/1/17
df.locale = Locale(identifier: "zh_Hans_CN")
df.dateStyle = .full
print("full 样式时间：" + df.string(from: now)) // full 样式时间：2022年1月17日 星期一
// 时间戳转 Date
let date = Date(timeIntervalSince1970: interval)
print(date) // 2022-01-17 06:11:41 +0000

import SwiftDate
// 使用 SwiftDate 库
let cn = Region(zone: Zones.asiaShanghai, locale: Locales.chineseChina)
SwiftDate.defaultRegion = cn
print("2008-02-14 23:12:14".toDate()?.year ?? "") // 2008
let d1 = "2022-01-17T23:20:35".toISODate(region: cn)
guard let d1 = d1 else {
    return
print(d1.minute) // 20
let d2 = d1 + 1.minutes
print(d2.minute)
// 两个 DateInRegion 相差时间 interval
let i1 = DateInRegion(Date(), region: cn) - d1
let s1 = i1.toString {
    $0.maximumUnitCount = 4
    $0.allowedUnits = [.day, .hour, .minute]
    $0.collapsesLargestUnit = true
    $0.unitsStyle = .abbreviated
    $0.locale = Locales.chineseChina
print(s1) // 9小时45分钟

// 计算两个时间之间相差多少时间，支持多种语言字符串
let d1 = Date().timeIntervalSince1970 - 60 * 60 * 24
let f1 = RelativeDateTimeFormatter()
f1.dateTimeStyle = .named
f1.formattingContext = .beginningOfSentence
f1.locale = Locale(identifier: "zh_Hans_CN")
let str = f1.localizedString(for: Date(timeIntervalSince1970: d1), relativeTo: Date())
print(str) // 昨天
// 简写
let str2 = Date.now.addingTimeInterval(-(60 * 60 * 24))
    .formatted(.relative(presentation: .named))
print(str2) // yesterday

// 描述多个事物
let s1 = ListFormatter.localizedString(byJoining: ["冬天","春天","夏天","秋天"])
print(s1)

// 名字
let f2 = PersonNameComponentsFormatter()
var nc1 = PersonNameComponents()
nc1.familyName = "戴"
nc1.givenName = "铭"
nc1.nickname = "铭哥"
print(f2.string(from: nc1)) // 戴铭
f2.style = .short
print(f2.string(from: nc1)) // 铭哥
f2.style = .abbreviated
print(f2.string(from: nc1)) // 戴
var nc2 = PersonNameComponents()
nc2.familyName = "Dai"
nc2.givenName = "Ming"
nc2.nickname = "Starming"
f2.style = .default
print(f2.string(from: nc2)) // Ming Dai
f2.style = .short
print(f2.string(from: nc2)) // Starming
f2.style = .abbreviated
print(f2.string(from: nc2)) // MD
// 取出名
let componets = f2.personNameComponents(from: "戴铭")
print(componets?.givenName ?? "") // 铭

// 数字
let f3 = NumberFormatter()
f3.locale = Locale(identifier: "zh_Hans_CN")
f3.numberStyle = .currency
print(f3.string(from: 123456) ?? "") // ¥123,456.00
f3.numberStyle = .percent
print(f3.string(from: 123456) ?? "") // 12,345,600%
let n1 = 1.23456
let n1Str = n1.formatted(.number.precision(.fractionLength(3)).rounded())
print(n1Str) // 1.235

// 地址
import Contacts
let f4 = CNPostalAddressFormatter()
let address = CNMutablePostalAddress()
address.street = "海淀区王庄路XX号院X号楼X门XXX"
address.postalCode = "100083"
address.city = "北京"
address.country = "中国"
print(f4.string(from: address))
/// 海淀区王庄路XX号院X号楼X门XXX
/// 北京 100083
/// 中国

// 参考：https://developer.apple.com/documentation/foundation/nsdimension
let m1 = Measurement(value: 1, unit: UnitLength.kilometers)
let m2 = m1.converted(to: .meters) // 千米转米
print(m2) // 1000.0 m
// 度量值转为本地化的值
let mf = MeasurementFormatter()
mf.locale = Locale(identifier: "zh_Hans_CN")
print(mf.string(from: m1)) // 1公里

面积 = 长度 × 长度
体积 = 长度 × 长度 × 长度 = 面积 × 长度
速度=长度/时间
加速度=速度/时间
力 = 质量 × 加速度
扭矩 = 力 × 长度
压力 = 力 / 面积
密度=质量 / 体积
能量 = 功率 × 时间
电阻 = 电压 / 电流

// 对数据的压缩
let d1 = "看看能够压缩多少？看看能够压缩多少？看看能够压缩多少？看看能够压缩多少？看看能够压缩多少？看看能够压缩多少？看看能够压缩多少？看看能够压缩多少？看看能够压缩多少？看看能够压缩多少？看看能够压缩多少？".data(using: .utf8)! as NSData
print("ori \(d1.count) bytes")
    /// 压缩算法
    /// * lz4
    /// * lzma
    /// * zlib
    /// * lzfse
    let compressed = try d1.compressed(using: .zlib)
    print("comp \(compressed.count) bytes")
    // 对数据解压
    let decomressed = try compressed.decompressed(using: .zlib)
    let deStr = String(data: decomressed as Data, encoding: .utf8)
    print(deStr ?? "")
} catch {}
/// ori 297 bytes
/// comp 37 bytes

let path1 = "/Users/mingdai/Downloads/1.html"
let path2 = "/Users/mingdai/Documents/GitHub/"
let u1 = URL(string: path1)
    // 写入
    let url1 = try FileManager.default.url(for: .itemReplacementDirectory, in: .userDomainMask, appropriateFor: u1, create: true) // 保证原子性安全保存
    print(url1)
    // 读取
    let s1 = try String(contentsOfFile: path1, encoding: .utf8)
    print(s1)
} catch {}
// 检查路径是否可用
let u2 = URL(fileURLWithPath:path2)
    let values = try u2.resourceValues(forKeys: [.volumeAvailableCapacityForImportantUsageKey])
    if let capacity = values.volumeAvailableCapacityForImportantUsage {
        print("可用: \(capacity)")
    } else {
        print("不可用")
} catch {
    print("错误: \(error.localizedDescription)")
}

// 遍历路径下所有目录
let u3 = URL(fileURLWithPath: FileManager.default.currentDirectoryPath)
let fm = FileManager.default
fm.enumerator(atPath: u3.path)?.forEach({ path in
    guard let path = path as? String else {
        return
    let url = URL(fileURLWithPath: path, relativeTo: u3)
    print(url.lastPathComponent)
})

// FileWrapper 的使用
// 创建文件
let f1 = FileWrapper(regularFileWithContents: Data("# 第 n 个文件\n ## 标题".utf8))
f1.fileAttributes[FileAttributeKey.creationDate.rawValue] = Date()
f1.fileAttributes[FileAttributeKey.modificationDate.rawValue] = Date()
// 创建文件夹
let folder1 = FileWrapper(directoryWithFileWrappers: [
    "file1.md": f1
folder1.fileAttributes[FileAttributeKey.creationDate.rawValue] = Date()
folder1.fileAttributes[FileAttributeKey.modificationDate.rawValue] = Date()
    try folder1.write(
        to: URL(fileURLWithPath: FileManager.default.currentDirectoryPath).appendingPathComponent("NewFolder"),
        options: .atomic,
        originalContentsURL: nil
} catch {}
print(FileManager.default.currentDirectoryPath)

let s1 = """
one1,
two2,
three3.
let sn1 = Scanner(string: s1)
while !sn1.isAtEnd {
    if let r1 = sn1.scanUpToCharacters(from: .newlines) {
        print(r1 as String)
/// one1,
/// two2,
/// three3.
// 找出数字
let sn2 = Scanner(string: s1)
sn2.charactersToBeSkipped = CharacterSet.decimalDigits.inverted // 不是数字的就跳过
var p: Int = 0
while !sn2.isAtEnd {
    if sn2.scanInt(&p) {
        print(p)
/// 1
/// 2
/// 3

var aStrs = [AttributedString]()
var aStr1 = AttributedString("""
正文内容，具体查看链接。
这里摘出第一个重点，还要强调的内容。
// 标题
let title = aStr1.range(of: "标题")
guard let title = title else {
    return aStrs
var c1 = AttributeContainer() // 可复用容器
c1.inlinePresentationIntent = .stronglyEmphasized
c1.font = .largeTitle
aStr1[title].setAttributes(c1)
// 链接
let link = aStr1.range(of: "链接")
guard let link = link else {
    return aStrs
var c2 = AttributeContainer() // 链接
c2.strokeColor = .blue
c2.link = URL(string: "https://ming1016.github.io/")
aStr1[link].setAttributes(c2.merging(c1)) // 合并 AttributeContainer
// Runs
let i1 = aStr1.range(of: "重点")
let i2 = aStr1.range(of: "强调")
guard let i1 = i1, let i2 = i2 else {
    return aStrs
var c3 = AttributeContainer()
c3.foregroundColor = .yellow
c3.inlinePresentationIntent = .stronglyEmphasized
aStr1[i1].setAttributes(c3)
aStr1[i2].setAttributes(c3)
for r in aStr1.runs {
    print("-------------")
    print(r.attributes)
aStrs.append(aStr1)
// Markdown
    let aStr2 = try AttributedString(markdown: """
    内容[链接](https://ming1016.github.io/)。需要**强调**的内容。
    aStrs.append(aStr2)
} catch {}

let ri = Int.random(in: 0..<10)
print(ri) // 0到10随机数
let a = [0, 1, 2, 3, 4, 5]
print(a.randomElement() ?? 0) // 数组中随机取个数
print(a.shuffled()) // 随机打乱数组顺序

enum UDKey {
    static let k1 = "token"
let ud = UserDefaults.standard
ud.set("xxxxxx", forKey: UDKey.k1)
let tk = ud.string(forKey: UDKey.k1)
print(tk ?? "")

struct S {
    static let shared = S()
    private init() {
        // 防止实例初始化
}

#if os(tvOS)
     // do something in tvOS
#elseif os(iOS)
     // do somthing in iOS
#elseif os(macOS)
    // do somthing in macOS
#endif

// 版本
@available(iOS 15, *)
func f() {
// 版本检查
if #available(iOS 15, macOS 12, *) {
} else {
    // nothing happen
}

#if canImport(SpriteKit)
   // iOS 等苹果系统执行
#else
   // 非苹果系统
#endif

#if targetEnvironment(simulator)
   // 模拟器
#else
   // 真机
#endif

@resultBuilder
struct RBS {
    // 基本闭包支持
    static func buildBlock(_ components: Int...) -> Int {
        components.reduce(0) { partialResult, i in
            partialResult + i
    // 支持条件判断
    static func buildEither(first component: Int) -> Int {
        component
    static func buildEither(second component: Int) -> Int {
        component
    // 支持循环
    static func buildArray(_ components: [Int]) -> Int {
        components.reduce(0) { partialResult, i in
            partialResult + i
let a = RBS.buildBlock(
print(a) // 6
// 应用到函数中
@RBS func f1() -> Int {
print(f1()) // 6
// 设置了 buildEither 就可以在闭包中进行条件判断。
@RBS func f2(stopAtThree: Bool) -> Int {
    if stopAtThree == true {
    } else {
print(f2(stopAtThree: false)) // 21
// 设置了 buildArray 就可以在闭包内使用循环了
@RBS func f3() -> Int {
    for i in 1...3 {
        i * 2
print(f3()) // 12

@dynamicMemberLookup
struct D {
    // 找字符串
    subscript(dynamicMember m: String) -> String {
        let p = ["one": "first", "two": "second"]
        return p[m, default: ""]
    // 找整型
    subscript(dynamicMember m: String) -> Int {
        let p = ["one": 1, "two": 2]
        return p[m, default: 0]
    // 找闭包
    subscript(dynamicMember m: String) -> (_ s: String) -> Void {
        return {
            print("show \($0)")
    // 静态数组成员
    var p = ["This is a member"]
    // 动态数组成员
    subscript(dynamicMember m: String) -> [String] {
        return ["This is a dynamic member"]
let d = D()
let s1: String = d.one
print(s1) // first
let i1: Int = d.one
print(i1) // 1
d.show("something") // show something
print(d.p) // ["This is a member"]
let dynamicP:[String] = d.dp
print(dynamicP) // ["This is a dynamic member"]

@dynamicCallable
struct D {
    // 带参数说明
    func dynamicallyCall(withKeywordArguments args: KeyValuePairs<String, Int>) -> Int {
        let firstArg = args.first?.value ?? 0
        return firstArg * 2
    // 无参数说明
    func dynamicallyCall(withArguments args: [String]) -> String {
        var firstArg = ""
        if args.count > 0 {
            firstArg = args[0]
        return "show \(firstArg)"
let d = D()
let i = d(numberIs: 2)
print(i) // 4
let s = d("hi")
print(s) // show hi

struct H: Hashable {
    var p1: String
    var p2: Int
    // 提供随机 seed
    func hash(into hasher: inout Hasher) {
        hasher.combine(p1)
let h1 = H(p1: "one", p2: 1)
let h2 = H(p1: "two", p2: 2)
var hs1 = Hasher()
hs1.combine(h1)
hs1.combine(h2)
print(h1.hashValue) // 7417088153212460033 随机值
print(h2.hashValue) // -6972912482785541972 随机值
print(hs1.finalize()) // 7955861102637572758 随机值
print(h1.hashValue) // 7417088153212460033 和前面 h1 一样
let h3 = H(p1: "one", p2: 1)
print(h3.hashValue) // 7417088153212460033 和前面 h1 一样
var hs2 = Hasher()
hs2.combine(h3)
hs2.combine(h2)
print(hs2.finalize()) // 7955861102637572758 和前面 hs1 一样

struct CommitModel: Decodable, Hashable {
  var sha: String
  var author: AuthorModel
  var commit: CommitModel
extension CommitModel: Identifiable {
  var id: String {
    return sha
}

import Combine
import Network
// 网络状态检查 network state check
final class Nsck: ObservableObject {
    static let shared = Nsck()
    private(set) lazy var pb = mkpb()
    @Published private(set) var pt: NWPath
    private let monitor: NWPathMonitor
    private lazy var sj = CurrentValueSubject<NWPath, Never>(monitor.currentPath)
    private var sb: AnyCancellable?
    init() {
        monitor = NWPathMonitor()
        pt = monitor.currentPath
        monitor.pathUpdateHandler = { [weak self] path in
            self?.pt = path
            self?.sj.send(path)
        monitor.start(queue: DispatchQueue.global())
    deinit {
        monitor.cancel()
        sj.send(completion: .finished)
    private func mkpb() -> AnyPublisher<NWPath, Never> {
        return sj.eraseToAnyPublisher()
}

var sb = Set<AnyCancellable>()
var alertMsg = ""
Nsck.shared.pb
    .sink { _ in
    } receiveValue: { path in
        alertMsg = path.debugDescription
        switch path.status {
        case .satisfied:
            alertMsg = ""
        case .unsatisfied:
            alertMsg = " "
        case .requiresConnection:
            alertMsg = " "
        @unknown default:
            alertMsg = " "
        if path.status == .unsatisfied {
            switch path.unsatisfiedReason {
            case .notAvailable:
                alertMsg += "网络不可用"
            case .cellularDenied:
                alertMsg += "蜂窝网不可用"
            case .wifiDenied:
                alertMsg += "Wifi不可用"
            case .localNetworkDenied:
                alertMsg += "网线不可用"
            @unknown default:
                alertMsg += "网络不可用"
    .store(in: &sb)

import SwiftUI
struct AnimateLayout: View {
 @State var changeLayout: Bool = true
 @Namespace var namespace
 var body: some View {
  VStack(spacing: 30) {
   if changeLayout {
    HStack { items }
   } else {
    VStack { items }
   Button("切换布局") {
    withAnimation { changeLayout.toggle() }
  .padding()
 @ViewBuilder var items: some View {
  Text("one")
   .matchedGeometryEffect(id: "one", in: namespace)
  Text("Two")
   .matchedGeometryEffect(id: "Two", in: namespace)
  Text("Three")
   .matchedGeometryEffect(id: "Three", in: namespace)
}

let d1 = Data("keyChain github token".utf8)
let service = "access-token"
let account = "github"
let q1 = [
    kSecValueData: d1,
    kSecClass: kSecClassGenericPassword,
    kSecAttrService: service,
    kSecAttrAccount: account
] as CFDictionary
// 添加一个 keychain
let status = SecItemAdd(q1, nil)
// 如果已经添加过会抛出 -25299 错误代码，需要调用 SecItemUpdate 来进行更新
if status == errSecDuplicateItem {
    let q2 = [
        kSecClass: kSecClassGenericPassword,
        kSecAttrService: service,
        kSecAttrAccount: account
    ] as CFDictionary
    let q3 = [
        kSecValueData: d1
    ] as CFDictionary
    SecItemUpdate(q2, q3)
// 读取
let q4 = [
    kSecAttrService: service,
    kSecAttrAccount: account,
    kSecClass: kSecClassGenericPassword,
    kSecReturnData: true
] as CFDictionary
var re: AnyObject?
SecItemCopyMatching(q4, &re)
guard let reData = re as? Data else { return }
print(String(decoding: reData, as: UTF8.self)) // keyChain github token
// 删除
let q5 = [
    kSecAttrService: service,
    kSecAttrAccount: account,
    kSecClass: kSecClassGenericPassword,
] as CFDictionary
SecItemDelete(q5)

@main // 要定义个静态的 main 函数
struct M {
  static func main() {
    print("let's begin")
}

import ArgumentParser
@main
struct C: ParsableCommand {
  @Argument(help: "Start")
  var phrase: String
  func run() throws {
    for _ in 1...5 {
      print(phrase)
}

import SQLite
struct DB {
    static let shared = DB()
    static let path = NSSearchPathForDirectoriesInDomains(
        .applicationSupportDirectory, .userDomainMask, true
    ).first!
    let BBDB: Connection?
    private init() {
            print(DB.path)
            BBDB = try Connection("\(DB.path)/github.sqlite3")
        } catch {
            BBDB = nil
        /// Swift 类型和 SQLite 类型对标如下：
        /// Int64 = INTEGER
        /// Double = REAL
        /// String = TEXT
        /// nil = NULL
        /// SQLite.Blob = BLOB
    // 创建表
    func cTbs() throws {
            try ReposNotiDataHelper.createTable()
            try DevsNotiDataHelper.createTable()
        } catch {
            throw DBError.connectionErr
enum DBError: Error {
    case connectionErr, insertErr, deleteErr, searchErr, updateErr, nilInData
protocol DataHelperProtocol {
    associatedtype T
    static func createTable() throws -> Void
    static func insert(i: T) throws -> Int64
    static func delete(i: T) throws -> Void
    static func findAll() throws -> [T]?
// MARK: 开发者更新提醒
typealias DBDevNoti = (
    login: String,
    lastReadId: String,
    unRead: Int
struct DevsNotiDataHelper: DataHelperProtocol {
    static let table = Table("devsNoti")
    static let login = Expression<String>("login")
    static let lastReadId = Expression<String>("lastReadId")
    static let unRead = Expression<Int>("unRead")
    typealias T = DBDevNoti
    static func createTable() throws {
        guard let db = DB.shared.BBDB else {
            throw DBError.connectionErr
            let _ = try db.run(table.create(ifNotExists: true) { t in
                t.column(login, unique: true)
                t.column(lastReadId, defaultValue: "")
                t.column(unRead, defaultValue: 0)
        } catch _ {
            throw DBError.connectionErr
    } // end createTable
    static func insert(i: DBDevNoti) throws -> Int64 {
        guard let db = DB.shared.BBDB else {
            throw DBError.connectionErr
        let insert = table.insert(login <- i.login, lastReadId <- i.lastReadId, unRead <- i.unRead)
            let rowId = try db.run(insert)
            guard rowId > 0 else {
                throw DBError.insertErr
            return rowId
        } catch {
            throw DBError.insertErr
    } // end insert
    static func delete(i: DBDevNoti) throws {
        guard let db = DB.shared.BBDB else {
            throw DBError.connectionErr
        let query = table.filter(login == i.login)
            let tmp = try db.run(query.delete())
            guard tmp == 1 else {
                throw DBError.deleteErr
        } catch {
            throw DBError.deleteErr
    } // end delete
    static func find(sLogin: String) throws -> DBDevNoti? {
        guard let db = DB.shared.BBDB else {
            throw DBError.connectionErr
        let query = table.filter(login == sLogin)
        let items = try db.prepare(query)
        for i in items {
            return DBDevNoti(login: i[login], lastReadId: i[lastReadId], unRead: i[unRead])
        return nil
    } // end find
    static func update(i: DBDevNoti) throws {
        guard let db = DB.shared.BBDB else {
            throw DBError.connectionErr
        let query = table.filter(login == i.login)
            if try db.run(query.update(lastReadId <- i.lastReadId, unRead <- i.unRead)) > 0 {
            } else {
                throw DBError.updateErr
        } catch {
            throw DBError.updateErr
    } // end update
    static func findAll() throws -> [DBDevNoti]? {
        guard let db = DB.shared.BBDB else {
            throw DBError.connectionErr
        var arr = [DBDevNoti]()
        let items = try db.prepare(table)
        for i in items {
            arr.append(DBDevNoti(login: i[login], lastReadId: i[lastReadId], unRead: i[unRead]))
        return arr
    } // end find all
}

// MARK: 初始化数据库
et db = DB.shared
    try db.cTbs() // 创建表
} catch {
}

do {
    if let fd = try ReposNotiDataHelper.find(sFullName: r.id) {
        reposDic[fd.fullName] = fd.unRead
    } else {
            let _ = try ReposNotiDataHelper.insert(i: DBRepoNoti(fullName: r.id, lastReadCommitSha: "", unRead: 0))
            reposDic[r.id] = 0
        } catch {
            return reposDic
} catch {
    return reposDic
}

import SwiftUI
struct SwiftPamphletApp: View {
    var body: some View {
        NavigationView {
            SPSidebar()
            Text("第二栏")
            Text("第三栏")
        .navigationTitle("Swift 小册子")
        .toolbar {
            ToolbarItem(placement: ToolbarItemPlacement.navigation) {
                Button {
                    NSApp.keyWindow?.firstResponder?.tryToPerform(#selector(NSSplitViewController.toggleSidebar(_:)), with: nil)
                } label: {
                    Label("Sidebar", systemImage: "sidebar.left")
struct SPSidebar: View {
    var body: some View {
        List {
            Section("第一组") {
                NavigationLink("第一项", destination: SPList(title: "列表1"))
                    .badge(3)
                NavigationLink("第二项", destination: SPList(title: "列表2"))
            Section("第二组") {
                NavigationLink("第三项", destination: SPList(title: "列表3"))
                NavigationLink("第四项", destination: SPList(title: "列表4"))
        .listStyle(SidebarListStyle())
        .frame(minWidth: 160)
        .toolbar {
            ToolbarItem {
                Menu {
                    Text("1")
                    Text("2")
                } label: {
                    Label("Label", systemImage: "slider.horizontal.3")
struct SPList: View {
    var title: String
    @State var searchText: String = ""
    var body: some View {
        List(0..<3) { i in
            Text("内容\(i)")
        .toolbar(content: {
            Button {
            } label: {
                Label("Add", systemImage: "plus")
        .navigationTitle(title)
        .navigationSubtitle("副标题")
        .searchable(text: $searchText)
}

struct ShareView: View {
    var s: String
    var body: some View {
        Menu {
            Button {
                let p = NSPasteboard.general
                p.declareTypes([.string], owner: nil)
                p.setString(s, forType: .string)
            } label: {
                Text("拷贝链接")
                Image(systemName: "doc.on.doc")
            Divider()
            ForEach(NSSharingService.sharingServices(forItems: [""]), id: \.title) { item in
                Button {
                    item.perform(withItems: [s])
                } label: {
                    Text(item.title)
                    Image(nsImage: item.image)
        } label: {
            Text("分享")
            Image(systemName: "square.and.arrow.up")
}

// 读取剪贴板内容
let s = NSPasteboard.general.string(forType: .string)
guard let s = s else {
    return
print(s)
// 设置剪贴板内容
let p = NSPasteboard.general
p.declareTypes([.string], owner: nil)
p.setString(s, forType: .string)

// 所有数相加
// 命令式思维
func sum1(arr: [Int]) -> Int {
  var sum: Int = 0
  for v in arr {
    sum += v
  return sum
// 声明式思维
func sum2(arr: [Int]) -> Int {
  return arr.reduce(0, +)
}

let pA = Just(0)
let _ = pA.sink { v in
    print("pA is: \(v)")
let pB = [7,90,16,11].publisher
let _ = pB
    .sink { v in
        print("pB: \(v)")
class AClass {
    var p: Int = 0 {
        didSet {
            print("property update to \(p)")
let o = AClass()
let _ = pB.assign(to: \.p, on: o)

import Combine
var cc = Set<AnyCancellable>()
struct S {
    let p1: String
    let p2: String
[S(p1: "1", p2: "one"), S(p1: "2", p2: "two")]
    .publisher
    .print("array")
    .sink {
        print($0)
    .store(in: &cc)

array: receive subscription: ([戴铭的Swift小册子.AppDelegate.(unknown context at $10ac82d20).(unknown context at $10ac82da4).S(p1: "1", p2: "one"), 戴铭的Swift小册子.AppDelegate.(unknown context at $10ac82d20).(unknown context at $10ac82da4).S(p1: "2", p2: "two")])
array: request unlimited
array: receive value: (S(p1: "1", p2: "one"))
S(p1: "1", p2: "one")
array: receive value: (S(p1: "2", p2: "two"))
S(p1: "2", p2: "two")
array: receive finished

import Combine
var cc = Set<AnyCancellable>()
struct S {
    let p1: String
    let p2: String
let pb = Just(S(p1: "1", p2: "one"))
    .print("pb")
    .sink {
        print($0)
    .store(in: &cc)

pb: receive subscription: (Just)
pb: request unlimited
pb: receive value: (S(p1: "1", p2: "one"))
S(p1: "1", p2: "one")
pb: receive finished

import Combine
var cc = Set<AnyCancellable>()
struct S {
    let p1: String
    let p2: String
enum CError: Error {
    case aE, bE
let ps1 = PassthroughSubject<S, CError>()
    .print("ps1")
    .sink { c in
        print("completion:", c) // send 了 .finished 后会执行
    } receiveValue: { s in
        print("receive:", s)
    .store(in: &cc)
ps1.send(S(p1: "1", p2: "one"))
ps1.send(completion: .failure(CError.aE)) // 和 .finished 一样后面就不会发送了
ps1.send(S(p1: "2", p2: "two"))
ps1.send(completion: .finished)
ps1.send(S(p1: "3", p2: "three"))
// 多个订阅者
let ps2 = PassthroughSubject<String, Never>()
ps2.send("one") // 订阅之前 send 的数据没有订阅者可以接收
ps2.send("two")
let sb1 = ps2
    .print("ps2 sb1")
    .sink { s in
    print(s)
ps2.send("three") // 这个 send 的值会被 sb1
let sb2 = ps2
    .print("ps2 sb2")
    .sink { s in
        print(s)
ps2.send("four") // 这个 send 的值会被 sb1 和 sb2 接受
sb1.store(in: &cc)
sb2.store(in: &cc)
ps2.send(completion: .finished)

ps1: receive subscription: (PassthroughSubject)
ps1: request unlimited
ps1: receive value: (S(p1: "1", p2: "one"))
receive: S(p1: "1", p2: "one")
ps1: receive error: (aE)
completion: failure(戴铭的Swift小册子.AppDelegate.(unknown context at $10b15ce10).(unknown context at $10b15cf3c).CError.aE)
ps2 sb1: receive subscription: (PassthroughSubject)
ps2 sb1: request unlimited
ps2 sb1: receive value: (three)
three
ps2 sb2: receive subscription: (PassthroughSubject)
ps2 sb2: request unlimited
ps2 sb1: receive value: (four)
ps2 sb2: receive value: (four)
ps2 sb1: receive finished
ps2 sb2: receive finished

import Combine
var cc = Set<AnyCancellable>()
struct S {
    let p1: String
    let p2: String
let ept = Empty<S, Never>() // 加上 completeImmediately: false 后面即使用 replaceEmpty 也不会接受值
    .print("ept")
    .sink { c in
        print("completion:", c)
    } receiveValue: { s in
        print("receive:", s)
    .store(in: &cc)
ept.replaceEmpty(with: S(p1: "1", p2: "one"))
    .sink { c in
        print("completion:", c)
    } receiveValue: { s in
        print("receive:", s)
    .store(in: &cc)

ept: receive subscription: (Empty)
ept: request unlimited
ept: receive finished
completion: finished
receive: S(p1: "1", p2: "one")
completion: finished

import Combine
var cc = Set<AnyCancellable>()
let cs = CurrentValueSubject<String, Never>("one")
cs.send("two")
cs.send("three")
let sb1 = cs
    .print("cs sb1")
    .sink {
        print($0)
cs.send("four")
cs.send("five")
let sb2 = cs
    .print("cs sb2")
    .sink {
        print($0)
cs.send("six")
sb1.store(in: &cc)
sb2.store(in: &cc)

cs sb1: receive subscription: (CurrentValueSubject)
cs sb1: request unlimited
cs sb1: receive value: (three)
three
cs sb1: receive value: (four)
cs sb1: receive value: (five)
cs sb2: receive subscription: (CurrentValueSubject)
cs sb2: request unlimited
cs sb2: receive value: (five)
cs sb1: receive value: (six)
cs sb2: receive value: (six)
cs sb1: receive cancel
cs sb2: receive cancel

import Combine
var cc = Set<AnyCancellable>()
let pb = ["one","two","three","three","four"]
    .publisher
let sb = pb
    .print("sb")
    .removeDuplicates()
    .sink {
        print($0)
sb.store(in: &cc)

sb: receive subscription: (["one", "two", "three", "three", "four"])
sb: request unlimited
sb: receive value: (one)
sb: receive value: (two)
sb: receive value: (three)
three
sb: receive value: (three)
sb: request max: (1) (synchronous)
sb: receive value: (four)
sb: receive finished

import Combine
var cc = Set<AnyCancellable>()
struct S {
    let p: AnyPublisher<String, Never>
let s1 = S(p: Just("one").eraseToAnyPublisher())
let s2 = S(p: Just("two").eraseToAnyPublisher())
let s3 = S(p: Just("three").eraseToAnyPublisher())
let pb = [s1, s2, s3].publisher
let sb = pb
    .print("sb")
    .flatMap {
    .sink {
        print($0)
sb.store(in: &cc)

sb: receive subscription: ([戴铭的Swift小册子.AppDelegate.(unknown context at $101167070).(unknown context at $1011670f4).S(p: AnyPublisher), 戴铭的Swift小册子.AppDelegate.(unknown context at $101167070).(unknown context at $1011670f4).S(p: AnyPublisher), 戴铭的Swift小册子.AppDelegate.(unknown context at $101167070).(unknown context at $1011670f4).S(p: AnyPublisher)])
sb: request unlimited
sb: receive value: (S(p: AnyPublisher))
sb: receive value: (S(p: AnyPublisher))
sb: receive value: (S(p: AnyPublisher))
three
sb: receive finished

import Combine
var cc = Set<AnyCancellable>()
let pb = PassthroughSubject<String, Never>()
let sb = pb
    .print("sb")
    .append("five", "six")
    .sink {
        print($0)
sb.store(in: &cc)
pb.send("one")
pb.send("two")
pb.send("three")
pb.send(completion: .finished)

sb: receive subscription: ([戴铭的Swift小册子.AppDelegate.(unknown context at $101167070).(unknown context at $1011670f4).S(p: AnyPublisher), 戴铭的Swift小册子.AppDelegate.(unknown context at $101167070).(unknown context at $1011670f4).S(p: AnyPublisher), 戴铭的Swift小册子.AppDelegate.(unknown context at $101167070).(unknown context at $1011670f4).S(p: AnyPublisher)])
sb: request unlimited
sb: receive value: (S(p: AnyPublisher))
sb: receive value: (S(p: AnyPublisher))
sb: receive value: (S(p: AnyPublisher))
three
sb: receive finished

import Combine
var cc = Set<AnyCancellable>()
let pb1 = PassthroughSubject<String, Never>()
let pb2 = ["nine", "ten"].publisher
let sb = pb1
    .print("sb")
    .prepend(pb2)
    .prepend(["seven","eight"])
    .prepend("five", "six")
    .sink {
        print($0)
sb.store(in: &cc)
pb1.send("one")
pb1.send("two")
pb1.send("three")

five
seven
eight
sb: receive subscription: (PassthroughSubject)
sb: request unlimited
sb: receive value: (one)
sb: receive value: (two)
sb: receive value: (three)
three
sb: receive cancel

import Combine
var cc = Set<AnyCancellable>()
let ps1 = PassthroughSubject<String, Never>()
let ps2 = PassthroughSubject<String, Never>()
let sb1 = ps1.merge(with: ps2)
    .sink {
        print($0)
ps1.send("one")
ps1.send("two")
ps2.send("1")
ps2.send("2")
ps1.send("three")
sb1.store(in: &cc)

sb1: receive subscription: (Merge)
sb1: request unlimited
sb1: receive value: (one)
sb1: receive value: (two)
sb1: receive value: (1)
sb1: receive value: (2)
sb1: receive value: (three)
three
sb1: receive cancel

import Combine
var cc = Set<AnyCancellable>()
let ps1 = PassthroughSubject<String, Never>()
let ps2 = PassthroughSubject<String, Never>()
let ps3 = PassthroughSubject<String, Never>()
let sb1 = ps1.zip(ps2, ps3)
    .print("sb1")
    .sink {
        print($0)
ps1.send("one")
ps1.send("two")
ps1.send("three")
ps2.send("1")
ps2.send("2")
ps1.send("four")
ps2.send("3")
ps3.send("一")
sb1.store(in: &cc)

sb1: receive subscription: (Zip)
sb1: request unlimited
sb1: receive value: (("one", "1", "一"))
("one", "1", "一")
sb1: receive cancel

import Combine
var cc = Set<AnyCancellable>()
let ps1 = PassthroughSubject<String, Never>()
let ps2 = PassthroughSubject<String, Never>()
let ps3 = PassthroughSubject<String, Never>()
let sb1 = ps1.combineLatest(ps2, ps3)
    .print("sb1")
    .sink {
        print($0)
ps1.send("one")
ps1.send("two")
ps1.send("three")
ps2.send("1")
ps2.send("2")
ps1.send("four")
ps2.send("3")
ps3.send("一")
ps3.send("二")
sb1.store(in: &cc)

sb1: receive subscription: (CombineLatest)
sb1: request unlimited
sb1: receive value: (("four", "3", "一"))
("four", "3", "一")
sb1: receive value: (("four", "3", "二"))
("four", "3", "二")
sb1: receive cancel

import Combine
var cc = Set<AnyCancellable>()
let sb1 = ["one","two","three"].publisher
    .print("sb1")
    .subscribe(on: DispatchQueue.global())
    .handleEvents(receiveOutput: {
        print("receiveOutput",$0)
    .receive(on: DispatchQueue.main)
    .sink {
        print($0)
sb1.store(in: &cc)

sb1: receive subscription: ([1, 2, 3])
sb1: request unlimited
sb1: receive value: (1)
receiveOutput 1
sb1: receive value: (2)
receiveOutput 2
sb1: receive value: (3)
receiveOutput 3
sb1: receive finished
3

let req = URLRequest(url: URL(string: "http://www.starming.com")!)
let dpPublisher = URLSession.shared.dataTaskPublisher(for: req)

//
// CombineSearchAPI.swift
// SwiftOnly (iOS)
// Created by Ming Dai on 2021/11/4.
import SwiftUI
import Combine
struct CombineSearchAPI: View {
  var body: some View {
    GithubSearchView()
// MARK: Github View
struct GithubSearchView: View {
  @State var str: String = "Swift"
  @StateObject var ss: SearchStore = SearchStore()
  @State var repos: [GithubRepo] = []
  var body: some View {
    NavigationView {
      List {
        TextField("输入：", text: $str, onCommit: fetch)
        ForEach(self.ss.repos) { repo -> GithubRepoCell in
          GithubRepoCell(repo: repo)
      .navigationTitle("搜索")
    .onAppear(perform: fetch)
  private func fetch() {
    self.ss.search(str: self.str)
struct GithubRepoCell: View {
  let repo: GithubRepo
  var body: some View {
    VStack(alignment: .leading, spacing: 20) {
      Text(self.repo.name)
      Text(self.repo.description)
// MARK: Github Service
struct GithubRepo: Decodable, Identifiable {
  let id: Int
  let name: String
  let description: String
struct GithubResp: Decodable {
  let items: [GithubRepo]
final class GithubSearchManager {
  func search(str: String) -> AnyPublisher<GithubResp, Never> {
    guard var urlComponents = URLComponents(string: "https://api.github.com/search/repositories") else {
      preconditionFailure("链接无效")
    urlComponents.queryItems = [URLQueryItem(name: "q", value: str)]
    guard let url = urlComponents.url else {
      preconditionFailure("链接无效")
    let sch = DispatchQueue(label: "API", qos: .default, attributes: .concurrent)
    return URLSession.shared
      .dataTaskPublisher(for: url)
      .receive(on: sch)
      .tryMap({ element -> Data in
        print(String(decoding: element.data, as: UTF8.self))
        return element.data
      .decode(type: GithubResp.self, decoder: JSONDecoder())
      .catch { _ in
        Empty().eraseToAnyPublisher()
      .eraseToAnyPublisher()
final class SearchStore: ObservableObject {
  @Published var query: String = ""
  @Published var repos: [GithubRepo] = []
  private let searchManager: GithubSearchManager
  private var cancellable = Set<AnyCancellable>()
  init(searchManager: GithubSearchManager = GithubSearchManager()) {
    self.searchManager = searchManager
    $query
      .debounce(for: .milliseconds(500), scheduler: RunLoop.main)
      .flatMap { query -> AnyPublisher<[GithubRepo], Never> in
        return searchManager.search(str: query)
          .map {
            $0.items
          .eraseToAnyPublisher()
      .receive(on: DispatchQueue.main)
      .assign(to: \.repos, on: self)
      .store(in: &cancellable)
  func search(str: String) {
    self.query = str
}

//
// CombineAPI.swift
// SwiftOnly (iOS)
// Created by Ming Dai on 2021/11/4.
import SwiftUI
import Combine
struct CombineAPI: View {
  var body: some View {
    RepListView(vm: .init())
struct RepListView: View {
  @ObservedObject var vm: RepListVM
  var body: some View {
    NavigationView {
      List(vm.repos) { rep in
        RepListCell(rep: rep)
      .alert(isPresented: $vm.isErrorShow) { () -> Alert in
        Alert(title: Text("出错了"), message: Text(vm.errorMessage))
      .navigationBarTitle(Text("仓库"))
    .onAppear {
      vm.apply(.onAppear)
struct RepListCell: View {
  @State var rep: RepoModel
  var body: some View {
    HStack() {
      VStack() {
        AsyncImage(url: URL(string: rep.owner.avatarUrl ?? ""), content: { image in
          image
            .resizable()
            .aspectRatio(contentMode: .fit)
            .frame(width: 100, height: 100)
        placeholder: {
          ProgressView()
            .frame(width: 100, height: 100)
        Text("\(rep.owner.login)")
          .font(.system(size: 10))
      VStack(alignment: .leading, spacing: 10) {
        Text("\(rep.name)")
          .font(.title)
        Text("\(rep.stargazersCount)")
          .font(.title3)
        Text("\(String(describing: rep.description ?? ""))")
        Text("\(String(describing: rep.language ?? ""))")
          .font(.title3)
      .font(.system(size: 14))
// MARK: Repo View Model
final class RepListVM: ObservableObject, UnidirectionalDataFlowType {
  typealias InputType = Input
  private var cancellables: [AnyCancellable] = []
  // Input
  enum Input {
    case onAppear
  func apply(_ input: Input) {
    switch input {
    case .onAppear:
      onAppearSubject.send(())
  private let onAppearSubject = PassthroughSubject<Void, Never>()
  // Output
  @Published private(set) var repos: [RepoModel] = []
  @Published var isErrorShow = false
  @Published var errorMessage = ""
  @Published private(set) var shouldShowIcon = false
  private let resSubject = PassthroughSubject<SearchRepoModel, Never>()
  private let errSubject = PassthroughSubject<APISevError, Never>()
  private let apiSev: APISev
  init(apiSev: APISev = APISev()) {
    self.apiSev = apiSev
    bindInputs()
    bindOutputs()
  private func bindInputs() {
    let req = SearchRepoRequest()
    let resPublisher = onAppearSubject
      .flatMap { [apiSev] in
        apiSev.response(from: req)
          .catch { [weak self] error -> Empty<SearchRepoModel, Never> in
            self?.errSubject.send(error)
            return .init()
    let resStream = resPublisher
      .share()
      .subscribe(resSubject)
    // 其它异步事件，比如日志等操作都可以做成Stream加到下面数组内。
    cancellables += [resStream]
  private func bindOutputs() {
    let repStream = resSubject
      .map {
        $0.items
      .assign(to: \.repos, on: self)
    let errMsgStream = errSubject
      .map { error -> String in
        switch error {
        case .resError: return "network error"
        case .parseError: return "parse error"
      .assign(to: \.errorMessage, on: self)
    let errStream = errSubject
      .map { _ in
      .assign(to: \.isErrorShow, on: self)
    cancellables += [repStream,errStream,errMsgStream]
protocol UnidirectionalDataFlowType {
  associatedtype InputType
  func apply(_ input: InputType)
// MARK: Repo Request and Models
struct SearchRepoRequest: APIReqType {
  typealias Res = SearchRepoModel
  var path: String {
    return "/search/repositories"
  var qItems: [URLQueryItem]? {
    return [
      .init(name: "q", value: "Combine"),
      .init(name: "order", value: "desc")
struct SearchRepoModel: Decodable {
  var items: [RepoModel]
struct RepoModel: Decodable, Hashable, Identifiable {
  var id: Int64
  var name: String
  var fullName: String
  var description: String?
  var stargazersCount: Int = 0
  var language: String?
  var owner: OwnerModel
struct OwnerModel: Decodable, Hashable, Identifiable {
  var id: Int64
  var login: String
  var avatarUrl: String?
// MARK: API Request Fundation
protocol APIReqType {
  associatedtype Res: Decodable
  var path: String { get }
  var qItems: [URLQueryItem]? { get }
protocol APISevType {
  func response<Request>(from req: Request) -> AnyPublisher<Request.Res, APISevError> where Request: APIReqType
final class APISev: APISevType {
  private let rootUrl: URL
  init(rootUrl: URL = URL(string: "https://api.github.com")!) {
    self.rootUrl = rootUrl
  func response<Request>(from req: Request) -> AnyPublisher<Request.Res, APISevError> where Request : APIReqType {
    let path = URL(string: req.path, relativeTo: rootUrl)!
    var comp = URLComponents(url: path, resolvingAgainstBaseURL: true)!
    comp.queryItems = req.qItems
    print(comp.url?.description ?? "url wrong")
    var req = URLRequest(url: comp.url!)
    req.addValue("application/json", forHTTPHeaderField: "Content-Type")
    let de = JSONDecoder()
    de.keyDecodingStrategy = .convertFromSnakeCase
    return URLSession.shared.dataTaskPublisher(for: req)
      .map { data, res in
        print(String(decoding: data, as: UTF8.self))
        return data
      .mapError { _ in
        APISevError.resError
      .decode(type: Request.Res.self, decoder: de)
      .mapError(APISevError.parseError)
      .receive(on: RunLoop.main)
      .eraseToAnyPublisher()
enum APISevError: Error {
  case resError
  case parseError(Error)
}

private final class KVOObject: NSObject {
  @objc dynamic var intV: Int = 0
  @objc dynamic var boolV: Bool = false
let o = KVOObject()
let _ = o.publisher(for: \.intV)
  .sink { v in
    print("value : \(v)")
  }

extension Notification.Name {
    static let noti = Notification.Name("nameofnoti")
let notiPb = NotificationCenter.default.publisher(for: .noti, object: nil)
        .sink {
            print($0)
        }

class A {
  var storage = Set<AnyCancellable>()
  init() {
    NotificationCenter.default.publisher(for: UIWindowScene.didEnterBackgroundNotification)
      .sink { _ in
        print("enter background")
      .store(in: &self.storage)