objective-c - UIWebView addSubview :UIImageView not displaying when triggered by touch events

Question

新的一天，新的问题!

我一直在开发一个应用程序，该应用程序需要在用户触摸屏幕时显示用户手指所在的圆圈。

我关注了 tutorial我发现子类化 UIWindow 和 my comment如果您使用 Storyboards 和 ARC，说明如何传递这些内容。

我正在使用以下代码(基于 this tutorial )来显示触摸指示器:

#pragma mark - Touch Events
- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
    NSArray *subviews = [self.webView subviews];
    for (UIView *view in subviews) 
    {
        // Check if view is scrollview
        if ([view isKindOfClass:[UserTouchImageView class]])
        {
            [view removeFromSuperview];
        }
    }

    // Enumerate over all the touches and draw a red dot on the screen where the touches were
    [touches enumerateObjectsUsingBlock:^(id obj, BOOL *stop) {
        // Get a single touch and it's location
        UITouch *touch = obj;
        CGPoint touchPoint = [touch locationInView:self.webView]; 

        // Add touch indicator
        UserTouchImageView *touchView = [[UserTouchImageView alloc] initWithFrame:CGRectMake(touchPoint.x -15, touchPoint.y -15, 30, 30)];
        [self.webView addSubview:touchView];
    }];
    NSLog(@"Touches began");
}
- (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event {
    NSArray *subviews = [self.webView subviews];
    for (UIView *view in subviews) 
    {
        // Check if view is scrollview
        if ([view isKindOfClass:[UserTouchImageView class]])
        {
            [view removeFromSuperview];
        }
    }

    // Enumerate over all the touches and draw a red dot on the screen where the touches were
    [touches enumerateObjectsUsingBlock:^(id obj, BOOL *stop) {
        // Get a single touch and it's location
        UITouch *touch = obj;
        CGPoint touchPoint = [touch locationInView:self.webView]; 

        // Draw a red circle where the touch occurred
        UserTouchImageView *touchView = [[UserTouchImageView alloc] initWithFrame:CGRectMake(touchPoint.x -15, touchPoint.y -15, 30, 30)];
        [self.webView addSubview:touchView];
    }];
    NSLog(@"Touches moved");
}
- (void) touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event {
    NSArray *subviews = [self.webView subviews];
    for (UIView *view in subviews) 
    {
        // Check if view is scrollview
        if ([view isKindOfClass:[UserTouchImageView class]])
        {
            [UIView animateWithDuration:0.5f 
                             animations:^{
                                 view.alpha = 0.0;
                             }
                             completion:^(BOOL finished) {
                                 [view removeFromSuperview];
                             }];
        }
    }
    NSLog(@"Touches ended");
}
- (void) touchesCancelled:(NSSet*)touches withEvent:(UIEvent*)event {
    NSArray *subviews = [self.webView subviews];
    for (UIView *view in subviews) 
    {
        // Check if view is scrollview
        if ([view isKindOfClass:[UserTouchImageView class]])
        {
            [view removeFromSuperview];
        }
    }
    NSLog(@"Touches cancelled");
}

UserTouchImageView 是 UIImageView 的子类，默认更改为:

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
        self.image = [UIImage imageNamed:@"greyCircle.png"];
        self.alpha = 0.5f;
    }
    return self;
}

我已经在没有 UIWebview 的情况下测试了此代码(将 self.webView 替换为 self.view )，它工作正常，在我单击并拖动的地方绘制圆圈，然后在我释放按钮时淡出。

我还成功实例化了 UserTouchImageView 并将其从 viewDidLoad 添加到 webView View Controller 的方法。

一旦我将 UIWebview 与上面的代码一起放入，同一行 ([self.webView addSubview:touchView];) 就不起作用。我仍然将 NSLog 消息发送到控制台，但 subview 没有明显添加。

谁能帮我弄清楚为什么这没有出现？是否有任何其他代码我需要注意，或者我不能这样做的任何原因？

非常感谢!

编辑

到目前为止，我已经上传了我的源 here (MediaFire)

编辑 2

我添加了以下两种方法:

-(void)listWebViewSubViews
{
    NSLog(@"BEGIN LISTING SUBVIEWS");
    for (UIView *view in [self.webView subviews]) {
        NSLog(@"Subview: %@", view.description);
    }
    NSLog(@"END LISTING SUBVIEWS");
}
-(void)view:(UIView *)view addTouchIndicatorWithCentreAtPoint:(CGPoint)point
{
    NSLog(@"View: %@, x: %f, y: %f", view.description, point.x, point.y);

    // Add touch indicator
    UserTouchImageView *touchView = [[UserTouchImageView alloc] initWithFrame:CGRectMake(point.x -15, point.y -15, 30, 30)];

    [view addSubview:touchView];


}

这些是从 UIWebView 外部的两个按钮和 touchesbegan 方法中调用的:

- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
    NSArray *subviews = [self.webView subviews];
    for (UIView *view in subviews) 
    {
        if ([view isKindOfClass:[UserTouchImageView class]])
        {
            [view removeFromSuperview];
        }
    }

    [touches enumerateObjectsUsingBlock:^(id obj, BOOL *stop) {
        UITouch *touch = obj;
        CGPoint touchPoint = [touch locationInView:self.webView]; 

        [self view:self.webView addTouchIndicatorWithCentreAtPoint:touchPoint];

        [self listWebViewSubViews];
    }];
    NSLog(@"Touches began");
}

日志似乎表明 self.webView 引用的 web View 在 内touches begin 方法是一个完全独立的实例，而不是从两个按钮引用的实例。我可以通过按钮添加多个 subview ，然后列出它们，它们都显示在日志中，但是当我点击模拟器时，这些额外的 subview 都没有列出。

有谁知道 UIWebView 中有任何特殊功能在触摸事件上有重复的实例？

Answer 1

一个 UIWebView不是一个 View ，而是 View 的集合。当您将 subview 添加到 UIWebView 时，新的 subview 将添加到 subview 的层次结构中。您的新 subview 可能被添加到其他不透明 View 后面。它在那里，但隐藏起来。我建议将此指示器 View 添加到层​​次结构中的不同 View 。