Unrecognized selector sent to instance when using UIPanGesture - swift2

Question

Hi I am trying to add UIPanGestureRecognizer to UIImageView (in my case, it's an emoji). All other UIGestureRecognizers such as long press, rotation, and pinch work well. However, it gives me an error: unrecognized selector sent to instance when I add UIPanGestureRecognizer. I've spent a day trying to figure out the reason but failed to fix it. Please help! Thanks in advance.
This is a function where I added UIGestureRecognizer to sticker
func emojiInsert(imageName: String) {
deleteButtonHides()
let stickerView: UIImageView = UIImageView(frame: CGRectMake(backgroundImage.frame.width/2 - 50, backgroundImage.frame.height/2 - 50, stickerSize, stickerSize))
stickerView.image = UIImage(named: imageName)
stickerView.userInteractionEnabled = true
stickerView.accessibilityIdentifier = "sticker"
let deleteStickerButton: UIImageView = UIImageView(frame: CGRectMake(stickerView.frame.width - 5 - stickerView.frame.width/3, 5, stickerView.frame.width/3, stickerView.frame.height/3))
deleteStickerButton.image = UIImage(named: "button_back")
deleteStickerButton.accessibilityIdentifier = "delete"
deleteStickerButton.userInteractionEnabled = true
deleteStickerButton.alpha = 0
deleteStickerButton.addGestureRecognizer(UITapGestureRecognizer(target: self, action: "deleteButtonTouches:"))
stickerView.addSubview(deleteStickerButton)
stickerView.addGestureRecognizer(UIPinchGestureRecognizer(target: self, action: "handlePinch:"))
stickerView.addGestureRecognizer(UIRotationGestureRecognizer(target: self, action: "handleRotate:"))
stickerView.addGestureRecognizer(UILongPressGestureRecognizer(target: self, action: "handleLongPress:"))
stickerView.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: "handlePan"))
print("emojiInsert : \(imageName)")
backgroundImage.addSubview(stickerView)
}
Below are call back functions I added in the end of the view.swift. I used touchesbegan and touchesMoved to drag an emoji but emoji moved in weird way after rotation. So now I am trying to use UIPanGesture to drag an emoji.
#IBAction func handlePinch(recognizer : UIPinchGestureRecognizer) {
if(deleteMode) {
return
}
print("handlePinch \(recognizer.scale)")
if let view = recognizer.view {
view.transform = CGAffineTransformScale(view.transform,
recognizer.scale, recognizer.scale)
recognizer.scale = 1
}
}
#IBAction func handleRotate(recognizer : UIRotationGestureRecognizer) {
if(deleteMode) {
return
}
if let view = recognizer.view {
view.transform = CGAffineTransformRotate(view.transform, recognizer.rotation)
recognizer.rotation = 0
}
}
#IBAction func handlePan(recognizer:UIPanGestureRecognizer) {
if(deleteMode) {
return
}
let translation = recognizer.translationInView(self.view)
if let view = recognizer.view {
view.center = CGPoint(x:view.center.x + translation.x,
y:view.center.y + translation.y)
}
recognizer.setTranslation(CGPointZero, inView: self.view)
}
#IBAction func handleLongPress(recognizer: UILongPressGestureRecognizer) {
if(recognizer.state == UIGestureRecognizerState.Began) {
if(!deleteMode) {
print("LongPress - Delete Shows")
for (_, stickers) in self.backgroundImage.subviews.enumerate() {
for (_, deleteButtons) in stickers.subviews.enumerate() {
if let delete:UIImageView = deleteButtons as? UIImageView{
if(delete.accessibilityIdentifier == "delete") {
delete.alpha = 1
}
}
}
}
deleteMode = true
} else {
deleteButtonHides()
}
}
}
Again, please help! Thanks in advance.

Answer 1

The problem is that you're missing a colon. In the following line:
stickerView.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: "handlePan"))
The handlePan should be handlePan:. That's because the Objective-C signature for your method is:
- (void)handlePan:(UIPanGestureRecognizer *)recognizer
The colon is part of the method name.