[ios] How to assign an action for UIImageView object in Swift

I'm trying to assign an UIImageView to an action when the user taps it.

I know how to create an action for a UIButton, but how could I mimic the same behavior of a UIButton, but using a UIImageView?

Swift 4 Code

Step 1 In ViewdidLoad()

   let pictureTap = UITapGestureRecognizer(target: self, action: #selector(MyInfoTableViewController.imageTapped))
       userImageView.addGestureRecognizer(pictureTap)
       userImageView.isUserInteractionEnabled = true

Step 2 Add Following Function

@objc func imageTapped() {

        let imageView = userImageView
        let newImageView = UIImageView(image: imageView?.image)
        newImageView.frame = UIScreen.main.bounds
        newImageView.backgroundColor = UIColor.black
        newImageView.contentMode = .scaleAspectFit
        newImageView.isUserInteractionEnabled = true
        let tap = UITapGestureRecognizer(target: self, action: #selector(dismissFullscreenImage))
        newImageView.addGestureRecognizer(tap)
        self.view.addSubview(newImageView)

        self.navigationController?.isNavigationBarHidden = true
        self.tabBarController?.tabBar.isHidden = true

    }

It's Tested And Working Properly

You need to add a a gesture recognizer (For tap use UITapGestureRecognizer, for tap and hold use UILongPressGestureRecognizer) to your UIImageView.

let tap = UITapGestureRecognizer(target: self, action: #selector(YourClass.tappedMe))
imageView.addGestureRecognizer(tap)
imageView.isUserInteractionEnabled = true

And Implement the selector method like:

@objc func tappedMe()
{
    println("Tapped on Image")
}

You can add a UITapGestureRecognizer to the imageView, just drag one into your Storyboard/xib, Ctrl-drag from the imageView to the gestureRecognizer, and Ctrl-drag from the gestureRecognizer to the Swift-file to make an IBAction.

You'll also need to enable user interactions on the UIImageView, as shown in this image:

Swift4 Code

Try this some new extension methods:

import UIKit

extension UIView {

    fileprivate struct AssociatedObjectKeys {
        static var tapGestureRecognizer = "MediaViewerAssociatedObjectKey_mediaViewer"
    }

    fileprivate typealias Action = (() -> Void)?


    fileprivate var tapGestureRecognizerAction: Action? {
        set {
            if let newValue = newValue {
                // Computed properties get stored as associated objects
                objc_setAssociatedObject(self, &AssociatedObjectKeys.tapGestureRecognizer, newValue, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN)
            }
        }
        get {
            let tapGestureRecognizerActionInstance = objc_getAssociatedObject(self, &AssociatedObjectKeys.tapGestureRecognizer) as? Action
            return tapGestureRecognizerActionInstance
        }
    }


    public func addTapGestureRecognizer(action: (() -> Void)?) {
        self.isUserInteractionEnabled = true
        self.tapGestureRecognizerAction = action
        let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(handleTapGesture))
        self.addGestureRecognizer(tapGestureRecognizer)
    }


    @objc fileprivate func handleTapGesture(sender: UITapGestureRecognizer) {
        if let action = self.tapGestureRecognizerAction {
            action?()
        } else {
            print("no action")
        }
    }

}

Now whenever we want to add a UITapGestureRecognizer to a UIView or UIView subclass like UIImageView, we can do so without creating associated functions for selectors!

Usage:

 profile_ImageView.addTapGestureRecognizer {
        print("image tapped")
    }

I suggest to place invisible(opacity = 0) button on your imageview and then handle interaction on button.

Need to add lazy for TapGestureRecognizer to register
since the 'self' in UITapGestureRecognizer(target: self ...) will be nil if it's not a lazy var. Even if you set isUserInteractionEnable = true, it won't register without lazy var.

lazy var imageSelector : UIImageView = {
    let image = UIImageView(image: "imageName.png")
    //now add tap gesture
    image.isUserInteractionEnabled = true
    image.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(handleImageSelector)))
    return image
}()
@objc private func handleImageSelector() {
    print("Pressed image selector")
}

You can put a UIButton with a transparent background over top of the UIImageView, and listen for a tap on the button before loading the image

For swift 2.0 and above do this

@IBOutlet weak var imageView: UIImageView!
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        let tap = UITapGestureRecognizer(target: self, action: #selector(ViewController.tappedMe))
        imageView.addGestureRecognizer(tap)
        imageView.userInteractionEnabled = true
    }
    func tappedMe()
    {
        print("Tapped on Image")
    }

You could actually just set the image of the UIButton to what you would normally put in a UIImageView. For example, where you would do:

myImageView.image = myUIImage

You could instead use:

myButton.setImage(myUIImage, forState: UIControlState.Normal)

So, here's what your code could look like:

override func viewDidLoad(){
  super.viewDidLoad()

  var myUIImage: UIImage //set the UIImage here
  myButton.setImage(myUIImage, forState: UIControlState.Normal)
}

@IBOutlet var myButton: UIButton!
@IBAction func buttonTap(sender: UIButton!){
  //handle the image tap
}

The great thing about using this method is that if you have to load the image from a database, you could set the title of the button before you set the image:

myButton.setTitle("Loading Image...", forState: UIControlState.Normal)

To tell your users that you are loading the image