iOS 获取当前正在显示的ViewController

1.我们在非视图类中想要随时展示一个view时，需要将被展示的view加到当前view的子视图，或用当前view presentViewController，或pushViewContrller，这些操作都需要获取当前正在显示的ViewController。

//获取当前屏幕显示的viewcontroller - (UIViewController *)getCurrentVC { UIViewController *result = nil; UIWindow * window = [[UIApplication sharedApplication] keyWindow]; if (window.windowLevel != UIWindowLevelNormal) { NSArray *windows = [[UIApplication sharedApplication] windows]; for(UIWindow * tmpWin in windows) { if (tmpWin.windowLevel == UIWindowLevelNormal) { window = tmpWin; break; } } } UIView *frontView = [[window subviews] objectAtIndex:0]; id nextResponder = [frontView nextResponder]; if ([nextResponder isKindOfClass:[UIViewController class]]) result = nextResponder; else result = window.rootViewController; // 显示TabBar的当前显示画面 if ([result isKindOfClass:[UITabBarController class]]) { UITabBarController *tabBar = (UITabBarController*)result; result = tabBar.selectedViewController; } // 显示Navigation的显示画面 if ([result isKindOfClass:[UINavigationController class]]) { UINavigationController *navigation = (UINavigationController*)result; result = navigation.topViewController; } return result; }

2.获取当前屏幕中present出来的viewcontroller。

- (UIViewController *)getPresentedViewController { UIViewController *appRootVC = [UIApplication sharedApplication].keyWindow.rootViewController; UIViewController *topVC = appRootVC; if (topVC.presentedViewController) { topVC = topVC.presentedViewController; } return topVC; }