iOS获取最顶层ViewController

知轮（杭州）科技有限公司 Android工程师

1.获取当前屏幕显示的 Viewcontroller 案例源码
2.UIApplication 的简析
3.KeyWindow 的简析
4.rootViewController 的简析
5.PresentedViewController 的简析

1 获取当前屏幕显示的 Viewcontroller

//获取当前屏幕显示的viewcontroller
- (UIViewController *)getCurrentVC
   ///下文中有分析
    UIViewController *rootViewController = [UIApplication sharedApplication].keyWindow.rootViewController;
    UIViewController *currentVC = [self getCurrentVCFrom:rootViewController];
    return currentVC;
- (UIViewController *)getCurrentVCFrom:(UIViewController *)rootVC
    UIViewController *currentVC;
    if ([rootVC presentedViewController]) {
        // 视图是被presented出来的
        rootVC = [rootVC presentedViewController];
    if ([rootVC isKindOfClass:[UITabBarController class]]) {
        // 根视图为UITabBarController
        currentVC = [self getCurrentVCFrom:[(UITabBarController *)rootVC selectedViewController]];  
    } else if ([rootVC isKindOfClass:[UINavigationController class]]){
        // 根视图为UINavigationController
        currentVC = [self getCurrentVCFrom:[(UINavigationController *)rootVC visibleViewController]];  
    } else {
        // 根视图为非导航类 
        currentVC = rootVC;