在一般應(yīng)用中，我們使用 addSubview 方法是添加到當(dāng)前控制器 ViewController 上的，但是對于某些情況下，我們需要把視圖添加到頂層控制器視圖上，即要獲取頂層視圖控制器。

• 當(dāng)前頂層窗口

    
    //UIWindow *window = [[UIApplication sharedApplication].windows lastObject];
    UIWindow *window = [UIApplication sharedApplication].keyWindow;
    // 添加到窗口
    [window addSubview:testView];

• 獲取View父視圖

- (UIViewController )viewController
{
    for (UIView next = [self superview]; next; next = next.superview) {
        UIResponder *nextResponder = [next nextResponder];
        if ([nextResponder isKindOfClass:[UIViewController class]]) {
            return (UIViewController *)nextResponder;
        }
    }
    return nil;
}

• 獲取最上層控制器|當(dāng)前控制器

//獲取當(dāng)前最上層的控制器
-(UIViewController *) getTopOrCurrentViewController
{
    UIWindow *topWindow = [UIApplication sharedApplication].keyWindow;
    if (topWindow.windowLevel != UIWindowLevelNormal)
    {
        topWindow = [self returnWindowWithWindowLevelNormal];
    }
    
    UIViewController *topController = topWindow.rootViewController;
    if(topController == nil)
    {
        topWindow = [UIApplication sharedApplication].delegate.window;
        if (topWindow.windowLevel != UIWindowLevelNormal)
        {
            topWindow = [self returnWindowWithWindowLevelNormal];
        }
        topController = topWindow.rootViewController;
    }
    
    while(topController.presentedViewController)
    {
        topController = topController.presentedViewController;
    }
    
    if([topController isKindOfClass:[UINavigationController class]])
    {
        UINavigationController *nav = (UINavigationController*)topController;
        topController = [nav.viewControllers lastObject];
        
        while(topController.presentedViewController)
        {
            topController = topController.presentedViewController;
        }
    }
    
    return topController;
}

-(UIWindow *) returnWindowWithWindowLevelNormal
{
    NSArray *windows = [UIApplication sharedApplication].windows;
    for(UIWindow *topWindow in windows)
    {
        if (topWindow.windowLevel == UIWindowLevelNormal)
            return topWindow;
    }
    return [UIApplication sharedApplication].keyWindow;
}