UILongPressGestureRecognizer not calling its target method

Question

This worked with devices on iOS 11, but with my device updated to iOS 12 it no longer works:

//the viewcontroller is initiated with UIGestureRecognizerDelegate

let longPressGesture = UILongPressGestureRecognizer(target: self, action: #selector(longPress))

//in cellForRowAt:
longPressGesture.minimumPressDuration = 1.0
longPressGesture.delegate = self
longPressGesture.cancelsTouchesInView = false
cell.addGestureRecognizer(longPressGesture)

@objc func longPress(longPressGestureRecognizer: UILongPressGestureRecognizer) {
     //never called
}

I also tried adding the gesture recognizer to a button in viewDidLoad to ensure it wasn't an issue with the tableview, and the longPress function is still not getting called.

Answer 1

 //the viewcontroller is initiated with UIGestureRecognizerDelegate let longPressGesture = UILongPressGestureRecognizer(target: self, action: #selector(longPress)) 

It looks like you are trying to make longPressGesture an instance property of your UIViewController while giving it a target and action as part of its initializer. That's not going to work, because at the time it is initialized, the target, self , is not the instance. There is no instance yet; the instance is what we are in the middle of creating!

Instead, move that line into cellForRowAt: , like this:

//in cellForRowAt:
let longPressGesture = UILongPressGestureRecognizer(target: self, action: #selector(longPress))
longPressGesture.minimumPressDuration = 1.0
longPressGesture.delegate = self
longPressGesture.cancelsTouchesInView = false
cell.addGestureRecognizer(longPressGesture)