UITapGestureRecognizer not working in UIImageView

Question

I had the following code:

UITapGestureRecognizer *showStoryTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(showNewsStory:)];
[showStoryTapRecognizer setDelegate:self];
[self.storyImageView_ addGestureRecognizer:showStoryTapRecognizer];
[showStoryTapRecognizer release];

This however doesn't trigger the showNewsStory, why is this? I have enabled userInteraction in the image view.

Mellisamellisent

is the ImageView in a tableview? – Pandiculation

Answer 1

UITapGestureRecognizer *oneTouch=[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(OneTouchHandeler)];

[oneTouch setNumberOfTouchesRequired:1];

[imageView addGestureRecognizer:oneTouch];

imageView.userInteractionEnabled = YES;

Kerakerala

Answer 2

You should enable user interaction for UIImageView object:

[self.storyImageView_ setUserInteractionEnabled:YES];

---

EDIT:

Try to remove the

[showStoryTapRecognizer setDelegate:self];

I don't think UITapGestureRecognizer has its delegate methods as far as I know.

Tiga

@Mellisamellisent actually, I thinks the code what you gave is fine (except the one I pointed out above). Maybe one of subviews covered the storyImageView_. – Tiga

@Tiga [self.storyImageView_ setUserInteractionEnabled:YES]; this was helpful. but UIGestureRecognizer is the super class of UITapGestureRecognizer, so we can set delegate when ever UIGestureRecognizerDelegate required. – Remora

That's the real answer. Rest of them did not work for me, except this one. – Ptero

@Ptero glad it helps :) – Tiga

Answer 3

UIImageView has user interaction disabled by default, unlike most other UIView subclasses in UIKit.

Countermand

UILabel has it disabled as well. – Flatways

Wasted a lot of time on this. Thank you. That checkbox is hidden away nicely ;) – Terry

Answer 4

I also noticed that in swift3, if you are adding a gesture recognizer which also looks for the target and the target is usually self, then you have to make the UIView to which you are adding the gesture recognizer to be a lazy var. Otherwise the gesture recognizer won't work. I think this is a bug in swift3. Ideally if you are accessing self in a variable before the class is fully initialized, it should throw an error. The code below won't detect gesture recognizer.

let messageImageView: CachedImageView = {
    let iv = CachedImageView()
    iv.translatesAutoresizingMaskIntoConstraints = false
    iv.layer.cornerRadius = 16
    iv.layer.masksToBounds = true
    iv.contentMode = .scaleAspectFill
    iv.isUserInteractionEnabled = true
    let zoomTap = UITapGestureRecognizer(target: self, action: #selector(handleZoomTap))
    zoomTap.numberOfTapsRequired = 1
    iv.addGestureRecognizer(zoomTap)
    return iv
}()

To fix that, you have to use lazy var

lazy var messageImageView: CachedImageView = {
    let iv = CachedImageView()
    iv.translatesAutoresizingMaskIntoConstraints = false
    iv.layer.cornerRadius = 16
    iv.layer.masksToBounds = true
    iv.contentMode = .scaleAspectFill
    iv.isUserInteractionEnabled = true
    let zoomTap = UITapGestureRecognizer(target: self, action: #selector(handleZoomTap))
    zoomTap.numberOfTapsRequired = 1
    iv.addGestureRecognizer(zoomTap)
    return iv
}()

Truly

That's a very helpful observation! I guess this happens because self doesn't yet exist when this method is called, so the gesture recognizer has no target. – Infold

Thanks! Yes, we should use lazy var instead of let to make sure self does exist when you tap it. – Martinet

Answer 5

Maybe ... action:@selector(showNewsStory) instead of action:@selector(showNewsStory:) . Please check it . Are there any other UITapGestureRecognizer in this controller ? Try this:

otherTapRecognizer.cancelsTouchesInView = NO;

Cookshop

That's okay, if the selector is wrong, it'll lead a crash of EXC_BAD_ACCESS. – Tiga

Answer 6

If you have already set imageView.userInteractionEnabled = YES; but the action still doesn't fire. Maybe it's because for one of superviews of imageView userInteractionEnabled is NO;

Puissance

Answer 7

objective-c ios 10

UITapGestureRecognizer *oneTouch=[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(OneTouchHandeler)];

[oneTouch setNumberOfTouchesRequired:1];

[imageView addGestureRecognizer:oneTouch];

imageView.userInteractionEnabled = YES;

// swift 3.0

   let oneTouch = UITapGestureRecognizer(target: self, action: #selector(self.OneTouchHandeler(_:)))

imageView.addGestureRecognizer(oneTouch)

imageView.isUserInteractionEnabled = true

Sphery

Answer 8

add

storyImageView.isUserInteractionEnabled = true;

Arbitration

Answer 9

if you allowed 2 different gesture, you should add below code snippet. For example, you use pickerView and also you want to detect tap gesture for same pickerView.

Asks the delegate if two gesture recognizers should be allowed to recognize gestures simultaneously.

Objective C

    -(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{
    return true;
}

Swift

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
    return true
}

Bowman

Answer 10

    use lazy var instead of let . Here is an example.

    lazy var loginSignUpView: LoginSignUpView = {
            let lsv = LoginSignUpView()
            lsv.loginRegisterButton.addTarget(self, action: #selector(handleLoginRegistrationButton), for: .touchUpInside)
            lsv.segmentedControlForLoginRegister.addTarget(self, action: #selector(handleSegmentedControlForLoginRegister), for: .valueChanged)
            lsv.profileImageView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(handleSelectProfileImageView)))

            return lsv
        }()


@objc func handleSelectProfileImageView() {
        print("Image tapped")
    }

Brynn