iOS获取当前显示页面controller

关于window

• UIWindow在显示的时候会根据UIWindowLevel进行排序的，即Level高的将排在所有Level比他低的层级的前面
• 当Level层级相同的时候，只有第一个设置为KeyWindow的显示出来，后面同级的再设置KeyWindow也不会显示

//获取到当前显示界面的controller
- (UIViewController *)getCurrentVC{
    
    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;
            }
        }
    }
    UIViewController *result = window.rootViewController;
    while (result.presentedViewController) {
        result = result.presentedViewController;
    }
    if ([result isKindOfClass:[BasicTabBarC class]]) {
        result = [(BasicTabBarC *)result selectedViewController];
    }
    if ([result isKindOfClass:[UINavigationController class]]) {
        result = [(UINavigationController *)result topViewController];
    }
    return result;
}