多个UIImageViews不响应触摸。

Question

I am working on an application which requires several UIImageViews to be added. A modal view controller is presented with different buttons. When dismissing the modal view controller it sends tag of the button which helps us deciding which UIImageView to add.

Now when I add first UIImageView, all the gestures work on it. But upon adding the second one, the first one loses response to touch.

The code to add the UIImageView (Body:UIImageView) is :

-(void) addBodyToStage:(int)index {
NSString * imageString = [NSString stringWithFormat:@"Body%i.png",index];
UIImage * image = [UIImage imageNamed:imageString];
Body * body = [[Body alloc] initWithImage:image];

//For Pan Gestures
[body setUserInteractionEnabled:YES];
[body addGestureRecognizer:panGesture];
[panGesture addTarget:body action:@selector(handlePan:)];

//For Pinch Gestures
[pinchGesture addTarget:body action:@selector(handlePinch:)];
[body addGestureRecognizer:pinchGesture];


//Adding to the view
[self.view addSubview:body];

}

Answer 1

do you initialize the gesture recognizers anywhere? It looks like you might be repurposing the same gesture recognizer to different imageViews. Try instantiating new gesture recognizers for each imageView

Answer 2

The same panGestureRecognizer, and pinchGestureRecognizer (the instance variable) has been added to all the imageViews. There is no problem with that per se, but I think you want different pan/pinch gesture recognizers for each imageView. The view will retain the gesture gesture recognizers so you can add the code in this method itself.

Go

  -(void) addBodyToStage:(int)index {
     NSString * imageString = [NSString stringWithFormat:@"Body%i.png",index];
    UIImage * image = [UIImage imageNamed:imageString];
    Body * body = [[Body alloc] initWithImage:image];

   //Alloc the pan/pinch gesture recognizers here
   //remember to alloc/init/autorelease (if not using ARC) 
   //else just alloc init
   //Remove the instantiation of those gesture recognizers in any other 
   //part of the  code.

   //For Pan Gestures
   [body setUserInteractionEnabled:YES];
   [body addGestureRecognizer:panGesture];
   [panGesture addTarget:body action:@selector(handlePan:)];

   //For Pinch Gestures
   [pinchGesture addTarget:body action:@selector(handlePinch:)];
   [body addGestureRecognizer:pinchGesture];


   //Adding to the view
   [self.view addSubview:body];

   }

Answer 3

Gesture recognizers can only be assigned to one view at a time. If you assign them to another view, they are implicitly unassigned from the first. You will need to initialize gesture recognizers for every view, or place the gesture recognizer on a view lower in the hierarchy and use the view property of the gesture recognizer to tell which one was touched.