Long press gesture on UICollectionViewCell

Question

I was wondering how to add a long press gesture recognizer to a (subclass of) UICollectionView. I read in the documentation that it is added by default, but I can\'t figure

Answer 1

Perhaps, using UILongPressGestureRecognizer is the most widespread solution. But I encounter with it two annoying troubles:

• sometimes this recognizer works in incorrect way when we're moving our touch;
• recognizer intercepts other touch actions so we can't use highlight callbacks of our UICollectionView in a proper way.

Let me suggest one a little bit bruteforce, but working as it's required suggestion:

Declaring a callback description for long click on our cell:

typealias OnLongClickListener = (view: OurCellView) -> Void

Extending UICollectionViewCell with variables (we can name it OurCellView, for example):

/// To catch long click events.
private var longClickListener: OnLongClickListener?

/// To check if we are holding button pressed long enough.
var longClickTimer: NSTimer?

/// Time duration to trigger long click listener.
private let longClickTriggerDuration = 0.5

Adding two methods in our cell class:

/**
 Sets optional callback to notify about long click.

 - Parameter listener: A callback itself.
 */
func setOnLongClickListener(listener: OnLongClickListener) {
    self.longClickListener = listener
}

/**
 Getting here when long click timer finishs normally.
 */
@objc func longClickPerformed() {
    self.longClickListener?(view: self)
}

And overriding touch events here:

/// Intercepts touch began action.
override func touchesBegan(touches: Set, withEvent event: UIEvent?) {
    longClickTimer = NSTimer.scheduledTimerWithTimeInterval(self.longClickTriggerDuration, target: self, selector: #selector(longClickPerformed), userInfo: nil, repeats: false)
    super.touchesBegan(touches, withEvent: event)
}

/// Intercepts touch ended action.
override func touchesEnded(touches: Set, withEvent event: UIEvent?) {
    longClickTimer?.invalidate()
    super.touchesEnded(touches, withEvent: event)
}

/// Intercepts touch moved action.
override func touchesMoved(touches: Set, withEvent event: UIEvent?) {
    longClickTimer?.invalidate()
    super.touchesMoved(touches, withEvent: event)
}

/// Intercepts touch cancelled action.
override func touchesCancelled(touches: Set?, withEvent event: UIEvent?) {
    longClickTimer?.invalidate()
    super.touchesCancelled(touches, withEvent: event)
}

Then somewhere in controller of our collection view declaring callback listener:

let longClickListener: OnLongClickListener = {view in
    print("Long click was performed!")
}

And finally in cellForItemAtIndexPath setting callback for our cells:

/// Data population.
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell", forIndexPath: indexPath)
    let castedCell = cell as? OurCellView
    castedCell?.setOnLongClickListener(longClickListener)

    return cell
}

Now we can intercept long click actions on our cells.