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POUIWebView addSubview:UIImageView not displaying when triggered by touch events
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copied!<p>A new day, a new question!</p> <p>I have been working on an app that requires I show a circle where the users finger(s) is(are) when they are touching the screen.</p> <p>I have followed a <a href="http://wyldco.com/blog/2010/11/how-to-capture-touches-over-a-uiwebview/" rel="nofollow">tutorial</a> I found on subclassing UIWindow, and <a href="http://wyldco.com/blog/2010/11/how-to-capture-touches-over-a-uiwebview/#comment-225" rel="nofollow">my comment</a> explains how to pass on those touches if you are using Storyboards and ARC.</p> <p>I am using the following code (which is based on <a href="http://mobile.tutsplus.com/tutorials/iphone/ios-quick-tip-detecting-touches/" rel="nofollow">this tutorial</a>) to make a touch indicator to display:</p> <pre><code>#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"); } </code></pre> <p>UserTouchImageView is a subclass of UIImageView, with the change to the default being:</p> <pre><code>- (id)initWithFrame:(CGRect)frame { self = [super initWithFrame:frame]; if (self) { // Initialization code self.image = [UIImage imageNamed:@"greyCircle.png"]; self.alpha = 0.5f; } return self; } </code></pre> <p>I've tested this code without a UIWebview (replacing the <code>self.webView</code> with <code>self.view</code>), and it works fine, drawing the circle where I click and drag, then fading out when I release the button.</p> <p>I have also succeeded in instantiating the UserTouchImageView and adding it to the webView from the <code>viewDidLoad</code> method of the viewController.</p> <p>As soon as I put the UIWebview in with the code above, the same line (<code>[self.webView addSubview:touchView];</code>) doesn't work. I still get the NSLog messages to the console, but the subview doesn't get visibly added.</p> <p>Can anyone help me figure out why this doesn't appear? Is there any other code I need to be aware of, or any reason why I cannot do this?</p> <p>Many thanks!</p> <p><strong>EDIT</strong></p> <p>I have uploaded my source so far <a href="http://www.mediafire.com/?y3sfy920sfama9a" rel="nofollow">here (MediaFire)</a></p> <p><strong>EDIT 2</strong></p> <p>I've added two methods as below:</p> <pre><code>-(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]; } </code></pre> <p>These are called from two buttons outside the UIWebView, and from within the touchesbegan method:</p> <pre><code>- (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"); } </code></pre> <p>The logging seems to indicate that the webview referenced by <code>self.webView</code> <strong>WITHIN</strong> the touches began method is an entirely seperate instance than the one when referenced from the two buttons. I can add multiple subviews via the button, and then list them, and they all show up in the logging, yet when I click to touch on the simulator, none of these extra subviews get listed.</p> <p>Does anyone know of any special functionality in a UIWebView to have a duplicate instance on touch events?</p>

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