Handling Multiple GestureRecognizers - swift

Question

I've run into an issue understanding UIGestureRecognizers. My goal right now is to have a set of GestureRecognizers to do different tasks, for example:
override func viewDidLoad() {
mainScene = GameScene(size: self.view.bounds.size)
main = view as! SKView
mainScene.panRecognizer = UIPanGestureRecognizer(target: self, action: #selector(shiftView(recognizer:)))
main.addGestureRecognizer(mainScene.panRecognizer)
mainScene.tapRecognizer = UITapGestureRecognizer(target: self, action: #selector(testTap(recognizer:)))
main.addGestureRecognizer(mainScene.tapRecognizer)
mainScene.pinchRecognizer = UIPinchGestureRecognizer(target: self, action: #selector(zoomView(recognizer:)))
main.addGestureRecognizer(mainScene.pinchRecognizer)
This is my game View Controller where I handle actions such as panning around a map, zooming, and tapping on map tiles. But I also want to be able to move sprites with a UITapGestureRecognizer so I also created this in my GameScene:
if startGame == true{
self.startGame()
for node in (self.tempGameBoard.landShipLayer.children as? Array<landship>)! {
node.landShipInteraction = UITapGestureRecognizer(target: self, action: #selector(handleTap(recognizer:)))
parentViewController.view.addGestureRecognizer(node.landShipInteraction)
}
}
The landShip in this case is representative of a sprite on screen that I would like to interact with via gesture recognizers.
My issue is that if I add this second set of recognizers, the tapping action becomes completely unresponsive. I can still zoom and pan, but the tapping behaviors I expect on my map tiles do not occur. I feel as though I am missing some understanding of how the gesture recognizers work.
Any ideas?
Thanks!

Answer 1

The UIGestureRecognizerDelegate has a special function managing simultaneous recognition of several gestures on the same object, that will do the trick.
1) Set your UIViewController to conform UIGestureRecognizerDelegate
2) Implement the following function:
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
if (gestureRecognizer == mainScene.panRecognizer || gestureRecognizer == mainScene.pinchRecognizer) && otherGestureRecognizer == mainScene.tapRecognizer {
return true
}
return false
}
In this particular example we allow the tap gesture to get triggered simultaneously with panning and pinching.
3) Then just assign the delegates to the pan and pinch gesture recognizers:
override func viewDidLoad() {
// your code...
// Set gesture recognizers delegates
mainScene.panRecognizer.delegate = self
mainScene.pinchRecognizer.delegate = self
}