detect a touch down event on UIImageView(s)

Question

I placed 4 UIImageView on UIView and I named them

UIImageView myImg1 = [[UIImageView alloc] init];     
UIImageView myImg2 = [[UIImageView alloc] init];     
UIImageView myImg3 = [[UIImageView alloc] init]; 
UIImageView myImg4 = [[UIImageView alloc] init];

How can I tell the compiler that I have just touched down UIImageView 1 or UIImaveView 2. If I only can use UIImageView to do this task, not buttons at all. Please guide me about this issue. Thanks

Answer 1

A stylish solution is to use the UIGestureRecognizer object:

in your loadView method (or anywhere you code the UIImageView (s) drawing...):

   UITapGestureRecognizer *tapRecognizer;
    UIImageView *anImageView = [[UIImageView alloc] initWithFrame:CGRectMake(20, 20, 100, 100)];
    [anImageView setTag:0]; //Pay attention here!, Tag is used to distinguish between your UIImageView on the selector
    [anImageView setBackgroundColor:[UIColor redColor]];
    [anImageView setUserInteractionEnabled:TRUE];
    tapRecognizer = [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(imageViewDidTapped:)] autorelease];
    tapRecognizer.numberOfTapsRequired = 1;
    [anImageView addGestureRecognizer:tapRecognizer];
    [contentView addSubview:anImageView];
    [anImageView release];

    UIImageView *anotherImageView = [[UIImageView alloc] initWithFrame:CGRectMake(80, 180, 100, 100)];
    [anotherImageView setTag:1]; //Pay attention here!, Tag is used to distinguish between your UIImageView on the selector
    [anotherImageView setBackgroundColor:[UIColor greenColor]];
    [anotherImageView setUserInteractionEnabled:TRUE];
    tapRecognizer = [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(imageViewDidTapped:)] autorelease];
    tapRecognizer.numberOfTapsRequired = 1;
    [anotherImageView addGestureRecognizer:tapRecognizer];
    [contentView addSubview:anotherImageView];
    [anotherImageView release];

This is a simple imageViewDidTapped: sample method that you can use to distinguish between the two sample UIImageView objects above:

- (void)imageViewDidTapped:(UIGestureRecognizer *)aGesture {
    UITapGestureRecognizer *tapGesture = (UITapGestureRecognizer *)aGesture;

    UIImageView *tappedImageView = (UIImageView *)[tapGesture view];

    switch (tappedImageView.tag) {
        case 0:
            NSLog(@"UIImageView 1 was tapped");
            break;
        case 1:
            NSLog(@"UIImageView 2 was tapped");
            break;
        default:
            break;
    }
}

Answer 2

You should consider using the tag property for this. Give each image a unique tag , then use this information to determine which image was touched. For example, set the tags by

UIImageView myImg1 = [[UIImageView alloc] init];     
myImg1.tag = 1;

and when you receive a touch for img , call

img.tag

to retrieve the tag.

Answer 3

UITapGestureRecognizer *singleFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];
        singleFingerTap.numberOfTapsRequired = 1;
        [myImg1 addGestureRecognizer:singleFingerTap];
        [myImg2 addGestureRecognizer:singleFingerTap];
        [singleFingerTap release];

And action method

-(void)handleSingleTap:(UIGestureRecognizer*)sender{
    //your code here
}

Answer 4

You can do like this.

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

        UITouch *touch = [touches anyObject];

       CGPoint touchLocation = [touch locationInView:self.view];
   if(CGRectContainsPoint(myImg1.view.frame,touchLocation))
 {
NSLog(@" Image 1");
}
else if(CGRectCont..

Note..the NSLog will be outputted if the point lies in more than one image view.. in that case..check which image view is on top..