UITapGestureRecognizer not working in UIImageView

Question

I had the following code:

UITapGestureRecognizer *showStoryTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(showNewsStory         


        

Answer 1

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
}()