UIPanGestureRecognizer does not work - swift

Question

It's weird, but when I add a UIPanGestureRecognizer to a view it does not work. It's my view, that white view is a subview of the red view:
Main View:
#IBOutlet weak var redView: UIView!
#IBOutlet weak var whiteView: UIView!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let panRecognizer = UIPanGestureRecognizer(target:self, action:#selector(ViewController.handlePan))
whiteView.gestureRecognizers = [panRecognizer]
}
func handlePan(recognizer:UIPanGestureRecognizer) {
//foo
}
When I tap and drag the white view it won't move.

Answer 1

try this:
whiteView.isUserInteractionEnabled = true

Answer 2

From the Apple's docs:
If the code for your pan gesture recognizer is not called, check to see if the following conditions are true, and make corrections as needed:
The isUserInteractionEnabled property of the view is set to true. Image views and labels set this property to false by default.
The number of touches is between the values specified in the minimumNumberOfTouches and maximumNumberOfTouches properties.
For a UIScreenEdgePanGestureRecognizer object, the edges property is configured and touches start at the appropriate edge.
Handling Pan Gestures

Answer 3

Here is the answer:
class ViewController: UIViewController {
#IBOutlet weak var redView: UIView!
#IBOutlet weak var whiteView: UIView!
var lastLocation:CGPoint = CGPointMake(0, 0)
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let panRecognizer = UIPanGestureRecognizer(target:self, action:#selector(ViewController.handlePan))
whiteView.addGestureRecognizer(panRecognizer)
}
func handlePan(recognizer:UIPanGestureRecognizer) {
let translation = recognizer.translationInView(redView)
whiteView.center = CGPointMake(lastLocation.x + translation.x, lastLocation.y + translation.y)
}
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
// Promote the touched view
lastLocation = whiteView.center
}
}

Answer 4

If you are using swift language for method you can't use [].
var PanGesture = UIPanGestureRecognizer(target: self, action: "respondToPanGesture:")
whiteView.addGestureRecognizer(PanGesture)
Hope it helps.