Detect touch of UIImage added as subview of UIScrollView

Question

I have UIScrollView with many UIImageViews .I need to drag and drop image from UIScrollView to another view. Outside the scrollView touch is worked. But inside scroll view touch is not worked. I used touchesBegan , touchesMoved etc method. Please help me.

-(IBAction)selectBut:(id)sender
{

 scrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(x,y,w,h)];

 scrollView.userInteractionEnabled = YES;

 int y = 0;

 for (int i = 0; i < [myArray count]; i++) {

UIImageView *image = [[UIImageView alloc]initWithFrame:CGRectMake(0, y, 75, 30)];

 image.userInteractionEnabled = YES;

  y=y+35;

 [scrollView addSubview:image];

}

[self.view addSubview:scrollView];

[scrollView setContentSize:CGSizeMake(150, 300)]

}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event

{

   UITouch *touch = [touches anyObject];

    if ([touch tapCount] == 1) {

        NSLog(@"One touch !!");
    }

}

Answer 1

you need to customize the UIImageView with your own view inherited from UIImageView . Provide touch methods in that customized subclass and add it on your UIScrollView ..

Subviews of UIScrollview will never call touchesBegan method directly. You need to customized with subview to get touchesBegan properties of that added subview/customized view.

I mean to say take subclass of ImageView like

CustomImageView *imageView = [[CustomImageView alloc] initWithFrame:CGRectMake(0, 0, 200, 200)];
[imageView setUserInteractionEnabled:YES];
[scrollView addSubview:imageView];
[imageView release];

CustomImageView class is should be inherited from UIImageView like

 @interface CustomImageView : UIImageView
  {
  }

in # .m File

  #import "CustomImageView.h"

@implementation CustomImageView


    - (id)initWithFrame:(CGRect)frame
   {
self = [super initWithFrame:frame];
if (self) {

}
return self;
}



    - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
      NSLog(@"%s", __FUNCTION__);

     }

    - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {


    }

    - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {


    UITouch *touch = [touches anyObject];

      if ([touch tapCount] == 2) {
    drawImageView.image = nil;
    return;
    }

     }

Answer 2

Add a Tap gesture recognizer to the scroll view for enabling touch inside scroll view:

UITapGestureRecognizer *singlTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(methodName:)];
singlTap.cancelsTouchesInView = NO; //Default value for cancelsTouchesInView is YES, which will prevent buttons to be clicked
[scrollViewName addGestureRecognizer:singlTap];

then write your code in specified method.

-(void)methodName:(UITapGestureRecognizer *)gesture
{
     //your code here
}

Answer 3

I don't know if this help you. But try to set the exclusiveTouch property of the UIImageView to YES .

Answer 4

Did you add your scrollview as an IBOutlet? If its from xib and as you say touches are available outside the scroll and not within, I guess you might have accidentally unchecked userInteractionEnabled for the scrollview which inhibits touch events. And you have added UIImageViews as subviews to UIScrollView. For UIImageView you have to first set userInteractionEnabled to YES and then add any gestures if necessary to get events or use the touchesBegan, touchesMoved methods. Unless you set interaction enabled you wont receive touch events on UIImageView. If the parent view I mean the UIScrollView's interaction is disabled you wont get touches on UIImageView too. Hope this helps :)