最近花了几天时间研究了一下怎么用iOS原生页面高效的更新app页面样式，我的思路是使用仿H5样式的JSON数据，利用各种布局（流动，线性等布局）来动态更新页面样式。
页面动态化主要的使用场景是app的电商页面，由于电商的业务需求较大，经常会需要改变各个banner的样式来满足业务的需求，所以需要客户端根据数据实时更新样式，下面说说我对页面动态化的理解跟思路。先看一下最后demo的效果：
其他app是怎么做的
用Charles抓包，发现京东跟网易考拉都是用type这个字段提前定义好各种banner的样式，通过后台返回的数据，来实现页面动态化更新，这样做有好的方面也有不好的地方：
好的方面：提前定义好banner的样式，客户端只需要定义好各个样式的UI，根据type字段来展现就好 不好的方面：只能根据定义好的样式来进行动态化更新，如果需要加入新的样式，需要提交新包 客户端不定义banner样式，而是定义布局样式来实现高度动态更新页面，思路来自于CSS里定义的div+CSS布局，CSS里可以根据display的inline跟block值来进行布局，iOS里，我定义了几种常见的布局：
<b>FlowLayout</b>：流式布局，根据display值横向或者纵向布局，根据屏幕宽度跟banner宽度换行 <b>LinearLayout</b>：线性布局，纵向布局 <b>WaterfallLayout</b>：瀑布流布局 <b>OneAndNLayout</b>：左边一个大图，右边N张小图的布局 <b>StickyLayout</b>：悬浮布局 页面动态化 整体架构如下：
Screenshot 2017-04-27 19.10.17.png每个UIViewController都是一个页面，页面是由一个个卡片组成的，卡片其实就是代表了一个布局样式，每个卡片是由一个个元素组成的，元素其实指的就是卡片布局样式下的各个banner，对应的JSON数据结构如下：
"cards": [ "layout": 1, "elements": [ "layout": 1, "elements": [由于大部分页面内容都需要上下滑动显示更多内容的，所以页面动态化的实现是基于
UICollectionView来做的，当然也可以使用UIScrollView来实现（淘宝天猫都是通过一个自定义具有回收复用机制的UIScrollView来展示动态化页面内容的），我的理解是既然UICollectionView可以通过自定义UICollectionViewLayout来展现自定义的cell，为什么不用还需要自己定义一个具有回收复用机制的UIScrollView去展现内容，UICollectionView自身就是带有回收复用机制的。我的具体实现，先看下整体的UML图：UICollectionViewLayout的自定义
UICollectionView提供的UICollectionViewFlowLayout并不能满足我的对样式展现的需求，所以这里我们必须自己写一套UICollectionViewLayout来提供对KBBaseElement里style字段里的样式支持，核心方法如下，具体实现在本文中不做过多详解，大家可以自己查询一下相关的知识：- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath UICollectionViewLayoutAttributes *layoutAttributes = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath]; NSInteger sectionLayout = 1; // CardFlowLayout is the default layout if (self.delegate && [self.delegate respondsToSelector:@selector(collectionView:layout:layoutForSection:)]) { sectionLayout = [self.delegate collectionView:self.collectionView layout:self layoutForSection:indexPath.section]; // CardFlowLayout 流式布局 if (sectionLayout == 1) { [self handleLayoutAttributesForFlowLayout:layoutAttributes atIndexPath:indexPath]; // CardLinearLayout 线性布局 if (sectionLayout == 2) { [self handleLayoutAttributesForLinearLayout:layoutAttributes atIndexPath:indexPath]; // CardOneAndNLayout 左边一张大图右边N张小图布局 if (sectionLayout == 3) { [self handleLayoutAttributesForOneAndNLayout:layoutAttributes atIndexPath:indexPath]; // CardWaterfallLayout 瀑布流布局 if (sectionLayout == 4) { [self handleLayoutAttributesForWaterfallLayout:layoutAttributes atIndexPath:indexPath]; return layoutAttributes;JSON数据
这里提供一个我自己创建的JSON mock数据，还有根据这个JSON数据最终展现出来的页面图
"cards": [ "layout": 1, "style": { "backgroundColor": "#ffffff" "elements": [ "type": 1, "image": "http://haitao.nos.netease.com/lqdbpar1xWZw5NuOB9ezf80UDm75Ei%2BZyMo%2BMgvE%2Bdunea_02T1704271119_480_240.jpg", "style": { "display": "inline", "margin": [ "0.75", "0.75" "width_ratio": 0.5, "width_height_ratio": 2.0 "type": 1, "image": "http://haitao.nos.netease.com/i11BQFE2dWpzplHNBV1Tr8Hafa5zTz%2BCoxF%2BwIBS%2BKF2Vx_03T1704261946_480_240.jpg", "style": { "display": "inline", "margin": [ "0.75", "0.75", "width_ratio": 0.5, "width_height_ratio": 2.0 "type": 1, "image": "http://haitao.nos.netease.com/KwaBThC4mguSnQCGBXVtfK4RmTTSeQ%2BZ5Ql%2BTNvQ%2BKNWzP_05T1704251128_480_240.jpg", "style": { "display": "inline", "margin": [ "0.75", "0.75" "width_ratio": 0.5, "width_height_ratio": 2.0 "type": 1, "image": "http://haitao.nos.netease.com/G4LGkdg7si4p5ZzVBZUKmkTq7EeTKt%2BRRaE%2BfQyx%2B6JlfC_06T1704251128_480_240.jpg", "style": { "display": "inline", "margin": [ "0.75", "0.75", "width_ratio": 0.5, "width_height_ratio": 2.0 "type": 1, "image": "http://haitao.nos.netease.com/HNkdnuFcFey5Om5GpNpO-C2LLgTrO3WtFT1704201935_960_210.jpg", "style": { "display": "block", "margin": [ "0.75", "width_height_ratio": 4.57 "type": 1, "image": "http://haitao.nos.netease.com/mrui23TlZJcRAocRWB70T1704262151_600_375.jpg", "style": { "display": "inline", "margin": [ "0.75", "0.75" "width_ratio": 0.7, "width_height_ratio": 1.6 "type": 1, "image": "http://haitao.nos.netease.com/ppiV8ODszIZciIZbmQih-A6HUakFq6g6oLTNhT1704201914_474_555.jpg", "style": { "display": "inline", "margin": [ "0.75", "0.75", "width_ratio": 0.3, "width_height_ratio": 0.685 "layout": 3, "style": { "backgroundColor": "#ffffff" "elements": [ "type": 1, "image": "http://haitao.nos.netease.com/KHASB80nO5JMsX1e2iChshdRT1704262150_480_480.jpg", "style": { "margin": [ "0.75" "width_ratio": 0.5, "width_height_ratio": 1.0 "type": 1, "image": "http://haitao.nos.netease.com/ygMuXb96hrtGtT6Wc9vZ2T17040101959_480_240.jpg", "style": { "margin": [ "0.75", "0.75", "width_ratio": 0.5, "width_height_ratio": 2.0 "type": 1, "image": "http://haitao.nos.netease.com/ADB5IaeoJWP9pIzVmwzkfGKhT1704262151_480_240.jpg", "style": { "margin": [ "0.75", "0.75", "width_ratio": 0.5, "width_height_ratio": 2.0 "layout": 1, "style": { "backgroundColor": "#ffffff" "elements": [ "type": 1, "image": "http://haitao.nos.netease.com/ppiV8ODszIZciIZbmQih-A6HUakFq6g6oLTNhT1704201914_474_555.jpg", "style": { "display": "inline", "margin": [ "0.75" "width_ratio": 0.5, "width_height_ratio": 0.856 "type": 1, "image": "http://haitao.nos.netease.com/mbO7ln3VxpAWxKkw84Ay-ys6BLHmk9LLRvwa4T1704201914_474_555.jpg", "style": { "display": "inline", "margin": [ "0.75", "width_ratio": 0.5, "width_height_ratio": 0.856 "layout": 2, "style": { "backgroundColor": "#ffffff" "elements": [ "type": 1, "image": "http://haitao.nos.netease.com/hwCkTs9AoDThXhv5k38dr2M0T1704242204_960_480.jpg", "style": { "margin": [ "10", "width_height_ratio": 2.0 "type": 1, "image": "http://haitao.nos.netease.com/Tt9TfxyDTSSirP27lXEiIsKPriT1704241519_960_480.jpg", "style": { "margin": [ "10", "width_height_ratio": 2.0 "type": 1, "image": "http://haitao.nos.netease.com/uey1sJ03lEOglRm626Th6dKrT1704242203_960_480.jpg", "style": { "margin": [ "10", "width_height_ratio": 2.0
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