获取当前viewcontroller

目前的话获取当前的ViewController分为两种情况
1.push过来的Viewcontroller
2.present出来的ViewController

下面就针对这两种情况来分别处理

1.push过来的VC

+ (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;
    return result;
}

2.present出来的VC

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