@interface AppDelegate ()

@end

 

@implementation AppDelegate

UIWindow * topWindow;//设置一个全局变量

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    self.window = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];

    [self.window makeKeyAndVisible];

　　//这里把topWindow设置在状态栏的位置。并设置放置最外层。加入一个手势。

    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

        topWindow = [[UIWindow alloc]init];

        topWindow.frame = [UIApplication sharedApplication].statusBarFrame;

        topWindow.backgroundColor = [UIColor redColor];

        topWindow.windowLevel = UIWindowLevelAlert;

        topWindow.hidden = NO;

        [topWindow addGestureRecognizer:[[UIGestureRecognizer alloc] initWithTarget:self action:@selector(topWindowClick)]];

    });

    return YES;

}

 

- (void)topWindowClick{

    UIWindow * window = [UIApplication sharedApplication].keyWindow;

    [self findScrollViewsInView:window];

}

 

- (void)findScrollViewsInView:(UIView *)view{

    for (UIView * subView in view.subviews) {//用个递归找到scrollView;

        [self findScrollViewsInView:subView];

    }    

    if (![view isKindOfClass:[UIScrollView class]]) return;

    UIView  * windowView = [UIApplication sharedApplication].keyWindow;

    BOOL interSect = CGRectIntersectsRect(windowView.bounds,[windowView convertRect:view.bounds fromView:nil] );

    if (!interSect) return;//如果有多个页面。这里判断拿到的页面是否是当前显示页面。如果是则滚动到顶部，否则跳过。

    UIScrollView * scrollView = (UIScrollView *)view;

    [scrollView scrollRectToVisible:CGRectMake(0, 0, 1, 1) animated:YES];    

}

 

***************************以下方法用于判断一个视图是否与当前视图重叠（该方法建议放在UIView的扩展中）**********************

- (BOOL)keyWindowinterSectWithView:(UIView *)view{

    UIWindow * window = [UIApplication sharedApplication].keyWindow;

    CGRect selfRect = [self convertRect:self.bounds fromView:window];

    CGRect viewRect = [view convertRect:view.bounds toView:window];

    return CGRectIntersectsRect(selfRect, viewRect);  

}