UIGestureRecognizer on UIImageView

Question

I have a UIImageView, which I want to be able to resize and rotate etc.

Can a UIGestureRecognizer be added to the UIImageView?

Answer 1

Swift 2.0 Solution

You create a tap, pinch or swipe gesture recognizer in the same manor. Below I'll walk you through 4 steps to getting your recognizer up and running.

4 Steps

1.) Inherit from UIGestureRecognizerDelegate by adding it to your class signature.

class ViewController: UIViewController, UIGestureRecognizerDelegate {...}

2.) Control drag from your image to your viewController to create an IBOutlet:

@IBOutlet weak var tapView: UIImageView!

3.) In your viewDidLoad add the following code:

// create an instance of UITapGestureRecognizer and tell it to run 
// an action we'll call "handleTap:"
let tap = UITapGestureRecognizer(target: self, action: Selector("handleTap:"))
// we use our delegate
tap.delegate = self
// allow for user interaction
tapView.userInteractionEnabled = true
// add tap as a gestureRecognizer to tapView
tapView.addGestureRecognizer(tap)

4.) Create the function that will be called when your gesture recognizer is tapped. (You can exclude the = nil if you choose).

func handleTap(sender: UITapGestureRecognizer? = nil) {
    // just creating an alert to prove our tap worked!
    let tapAlert = UIAlertController(title: "hmmm...", message: "this actually worked?", preferredStyle: UIAlertControllerStyle.Alert)
    tapAlert.addAction(UIAlertAction(title: "OK", style: .Destructive, handler: nil))
    self.presentViewController(tapAlert, animated: true, completion: nil)
}

---

Your final code should look something like this:

class ViewController: UIViewController, UIGestureRecognizerDelegate {

    @IBOutlet weak var tapView: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()

        let tap = UITapGestureRecognizer(target: self, action: Selector("handleTap:"))
        tap.delegate = self
        tapView.userInteractionEnabled = true
        tapView.addGestureRecognizer(tap)
    }

    func handleTap(sender: UITapGestureRecognizer? = nil) {
        let tapAlert = UIAlertController(title: "hmmm...", message: "this actually worked?", preferredStyle: UIAlertControllerStyle.Alert)
        tapAlert.addAction(UIAlertAction(title: "OK", style: .Destructive, handler: nil))
        self.presentViewController(tapAlert, animated: true, completion: nil)
    }
}