Touch method UIImageView inside UIScrollView - objective-c

Question

I am wondering how I can use a touch method for a UIImageView inside a UIScrollView in xCode.
When I add the UIImageView subview to the self.view, I can use the touch method. But when I add the UIImageView subview to the UIScrollView, I can't. How can I solve this?
This is my code:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
touches = [event allTouches];
for (UITouch *touch in touches) {
NSLog(#"Image Touched");
}
}
- (void)viewDidLoad
{
[super viewDidLoad];
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 44, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height * 0.9)];
scrollView.scrollEnabled = TRUE;
scrollView.bounces = TRUE;
scrollView.contentSize = CGSizeMake([UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height);
scrollView.userInteractionEnabled = YES;
[self.view addSubview:scrollView];
UIImageView *ImageView = [UIImageView alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width * 0.04, 10, [UIScreen mainScreen].bounds.size.width * 0.28, [UIScreen mainScreen].bounds.size.height * 0.22)];
ImageView.image = [UIImage imageNamed(#"image.png")];
ImageView.layer.borderColor = [UIColor whiteColor].CGColor;
ImageView.layer.borderWidth = 1;
ImageView.userInteractionEnabled = YES;
[scrollView addSubview:ImageView];
}

Answer 1

Give UIGestureRecognizers a try. They are far easier to manage with multiple layers of touch management.
- (void)touchedImage:(UITapGestureRecognizer *)gesture {
// When the gesture has ended, perform your action.
if (gesture.state == UIGestureRecognizerStateEnded) {
NSLog(#"Touched Image");
}
}
- (void)viewDidLoad
{
[super viewDidLoad];
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 44, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height * 0.9)];
scrollView.scrollEnabled = TRUE;
scrollView.bounces = TRUE;
scrollView.contentSize = CGSizeMake([UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height);
scrollView.userInteractionEnabled = YES;
[self.view addSubview:scrollView];
UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width * 0.04, 10, [UIScreen mainScreen].bounds.size.width * 0.28, [UIScreen mainScreen].bounds.size.height * 0.22)];
imageView.image = [UIImage imageNamed:#"image.png"];
imageView.layer.borderColor = [UIColor whiteColor].CGColor;
imageView.layer.borderWidth = 1;
imageView.userInteractionEnabled = YES;
[scrollView addSubview:imageView];
// Create a tap gesture
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(touchedImage:)];
[imageView addGestureRecognizer:tap];
}

Answer 2

if you're dealing with multiple imageviews using the same gesture recognizer, it won't work. Try using a new gesture recognizer per image view.

Answer 3

User interaction of UIImageView is disabled by default you can enable it by setting imageView.userInteractionEnabled = YES;

Answer 4

You'll have to derive a CustomScrollView from UIScrollView and override all touches method like touchesBegan,Moved,Ended and Cancelled like below:
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
for (UIView *view in self.subviews)
{
UITouch *touch = [touches anyObject];
CGPoint pt = [touch locationInView:view];
if (CGRectContainsPoint(view.frame, pt))
{
[view touchesMoved:touches withEvent:event];
}
}
}
After you do this. When you add any view in the instance of customScrollView, you'll get the touches in the added view properly.

Answer 5

I had the same problem with an image view as a subview in a scroll view when applying a transformation.
Upon scroll my gesture recognizer no longer worked so I checked the offset of the scroll view and reset my image so the gesture was recognized.
And of course we need to set userInterActionEnabled to true and add the gesture in viewDidLoad()
override func viewDidLoad() {
imageView.userInteractionEnabled = true
addGesture()
}
func addGesture(){
let singleTap = UITapGestureRecognizer(target: self, action: #selector(MyViewController.enableGesture(_:)));
singleTap.numberOfTapsRequired = 1
self.imageView.addGestureRecognizer(singleTap)
self.imageView.tag = 1
}
override func scrollViewDidScroll(scrollView: UIScrollView) {
let offset = scrollView.contentOffset.y
if offset > 0 {
imageView.layer.transform = avatarTransform
}
else {
imageView.transform = CGAffineTransformIdentity
}
}