UITapGestureRecognizer unrecognized selector sent to instance

Question

I've searched for solutions to this problem but couldn't find anything that seems to address it in my case. I'm getting the above exception from a UITapGestureRecognizer.

Here's the simplified code:

import UIKit;

class ViewController : UIViewController, UIScrollViewDelegate
{
    @IBOutlet weak var scrollView:UIScrollView!;
    var imageView:UIImageView!;

    override func viewDidLoad()
    {
        super.viewDidLoad();

        ... set up imageView/scrollView here ...

        let doubleTapRecognizer = UITapGestureRecognizer(target: self, action: "onScrollViewDoubleTapped");
        doubleTapRecognizer.numberOfTapsRequired = 2;
        doubleTapRecognizer.numberOfTouchesRequired = 1;
        scrollView.addGestureRecognizer(doubleTapRecognizer);
    }


    func onScrollViewDoubleTapped(recognizer:UITapGestureRecognizer)
    {
    }
}

Can anyone tell what is wrong with this code? It seems all correct to me. I suspect that it has to do with assigning ViewController as delegate to scrollView (or vice versa)? However the ViewController is set as the delegate to scrollView. But maybe it's something else that causes this error?

score 24 · Accepted Answer · answered Jul 29 '14 at 17:38

24

Try adding a colon to your selector string.

let doubleTapRecognizer = UITapGestureRecognizer(target: self, action: "onScrollViewDoubleTapped:");

As cabellicar123 mentioned, this indicates that the selector takes an argument.

answered Jul 29 '14 at 17:38

Connor Pearson

63,902
28
145
142

2

To explain further the `:` indicated that it is expecting an argument. – carloabelli Jul 29 '14 at 17:38
Aha! Thanks, that fixes it! Didn't know about the colon. – BadmintonCat Jul 29 '14 at 17:43

Daniel Storm · Answer 2 · 2021-04-04T15:03:41.227

5

Swift 4 using #selector.

let tapGesture: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(didSelectItem(sender:)))

@objc func didSelectItem(sender: AnyObject?) {
    print("didSelectItem: \(sender)")
}

edited Apr 04 '21 at 15:03

answered Dec 06 '17 at 22:56

Daniel Storm

18,301
9
84
152

score 2 · Answer 3 · answered Jul 29 '15 at 07:35

2

Also try adding a parameter to your method:

...(target: self, action: "yourMethodName:")

func yourMethodName(sender: AnyObject?)
{
    println("Clicked yourMethodName")
}

answered Jul 29 '15 at 07:35

ODAXY

335
4
12

score 1 · Answer 4 · answered Feb 10 '16 at 14:35

Maybe could help someone: I had this error because I declared private the selector method:

func setup() {
  let singleFingerTap = UITapGestureRecognizer(target: self, action: "didTapOnViewInteraction:")
  singleFingerTap.numberOfTapsRequired = 1
  self.viewInteraction.addGestureRecognizer(singleFingerTap)
}

private func didTapOnViewInteraction(recognizer: UITapGestureRecognizer) {

}

Removing "private" keyword, all works great!

score 1 · Answer 5 · answered Dec 12 '17 at 07:37

for swift 4

override func viewDidLoad() {
        super.viewDidLoad()

    let tap = UITapGestureRecognizer(target: self, action: #selector(SignUpViewController.click))
    userImage.addGestureRecognizer(tap)
    userImage.isUserInteractionEnabled = true
}

@objc func click()
{
    print("Tapped on Image")
}

where SignUpViewController is your viewcontroller name

score 0 · Answer 6 · answered Feb 16 '18 at 17:16

In my case, with Swift 4, the selector was correctly defined, but since the item with the gesture was inside a collection view, it was causing the selector not to be found. I implemented a custom cell and configured the selector inside of it

let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "recent", for: indexPath) as! MyCollectionViewCell

cell.configureGestureWith(entry: recentEntries.sorted(by: {$0.createdAt > $1.createdAt})[indexPath.row], sender: self)

Hope this helps some one.

UITapGestureRecognizer unrecognized selector sent to instance

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