iOS 获取当前的UIViewController

//获取当前屏幕显示的viewcontroller

+(UIViewController *)getCurrentWindowVC

{

    UIViewController *result = nil;

    UIWindow * window = [[UIApplication sharedApplication] keyWindow];

    if (window.windowLevel != UIWindowLevelNormal)

    {

        NSArray *windows = [[UIApplication sharedApplication] windows];

        for(UIWindow * tempWindow in windows)

        {

            if (tempWindow.windowLevel == UIWindowLevelNormal)

            {

                window = tempWindow;

                break;

            }

        }

    }

    UIView *frontView = [[window subviews] objectAtIndex:0];

    id nextResponder = [frontView nextResponder];

    if ([nextResponder isKindOfClass:[UIViewController class]])

    {

        result = nextResponder;

    }

    else

    {

        result = window.rootViewController;

    }

    return  result;

}