##参数传入导航试图控制器或者UITabBarController self.window.rootViewController 也可。

+ (UIViewController *)topViewControllerWithRootViewController:(UIViewController*)rootViewController{    if ([rootViewController isKindOfClass:[UITabBarController class]]) {        UITabBarController *tabBarController = (UITabBarController *)rootViewController;        return [self topViewControllerWithRootViewController:tabBarController.selectedViewController];    } else if ([rootViewController isKindOfClass:[UINavigationController class]]) {        UINavigationController* navigationController = (UINavigationController*)rootViewController;        return [self topViewControllerWithRootViewController:navigationController.visibleViewController];    } else if (rootViewController.presentedViewController) {        UIViewController* presentedViewController = rootViewController.presentedViewController;        return [self topViewControllerWithRootViewController:presentedViewController];    } else {        return rootViewController;    }}复制代码

另一种方法