Swift : Set UIPanGestureRecognizer to UIView

Question

Im trying to set up a UIPanGestureRecognizer to a specific UIView

    self.halfViewBlue.frame = CGRectMake(0, 0, self.bounds.width / 2, self.bounds.height)
    self.halfViewBlue.backgroundColor = UIColor.blueColor()
    halfViewBlue.alpha = 1.0
    self.addSubview(self.halfViewBlue)

    self.halfViewRed.frame = CGRectMake(self.frame.midX, 0, self.bounds.width / 2, self.bounds.height)
    self.halfViewRed.backgroundColor = UIColor.redColor()
    halfViewRed.alpha = 1.0
    self.addSubview(self.halfViewRed)

    //Pan Gesture for Red
    let panGestureRed = UIPanGestureRecognizer()
    panGestureRed.addTarget(self, action: "handlePanRed:")
    self.addGestureRecognizer(panGestureRed)
    self.userInteractionEnabled = true

    //Pan Gesture for Blue
    let panGestureBlue = UIPanGestureRecognizer()
    panGestureBlue.addTarget(self, action: "handlePanBlue:")
    self.addGestureRecognizer(panGestureBlue)
    self.userInteractionEnabled = true

}

func handlePanRed(gesture : UIPanGestureRecognizer){

    if (gesture.state == UIGestureRecognizerState.Changed || gesture.state == UIGestureRecognizerState.Ended){

        let velocity : CGPoint = gesture.velocityInView(halfViewRed)

        //Pan Down
        if(velocity.y > 0){
            print("Panning down")
            hideRedBar()
            produceBlueBar()
        }
        //Pan Up
        if(velocity.y < 0){
            print("panning up")
            hideBlueBar()
            produceRedBar()
        }
    }
}


func handlePanBlue(gesture : UIPanGestureRecognizer){

    if (gesture.state == UIGestureRecognizerState.Changed || gesture.state == UIGestureRecognizerState.Ended){

        let velocity : CGPoint = gesture.velocityInView(halfViewBlue)

        //Pan Down
        if(velocity.y > 0){
            print("Panning down")
            hideBlueBar()
            produceRedBar()
                        }

        if(velocity.y < 0){
            print("panning up")
            hideRedBar()
            produceBlueBar()

        }
    }
}

Here I simply create two UIViews, both split vertically across the screen(equally). I then add two panGestures and a function to follow it. My issue is that the only panGesture that gets recognized is the "panGestureBlue" and weirdly i can control it on any part of the screen, not just the half where the "halfViewBlue" is. So I'm assuming that both panGestures are being added to self.view and not the UIView it is suppose to be put with, and the "panGestureBlue" is being read in because it is added after "panGestureRed". Instead of "self" in the "panGestureBlue.addTarget" i tried putting "halfViewBlue", but it crashed.

How can i fix this issue!?

Answer 1

You should add the pan gesture on the subviews not the superview, like this:

self.halfViewRed.addGestureRecognizer(panGestureRed)
self.halfViewBlue.addGestureRecognizer(panGestureBlue)