detect a touch down event on UIImageView(s) - iphone

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..