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iosobjective-cswiftuiviewgesture

UIPinchGesture ? why it show the scaled result only after I rotate the device

I am try to use UIPinchGesture to scale a simple face that I draw by bezierPath, but when I use two finger to pinch the screen (either make it bigger or smaller), it does not show me result, only when I rotate the device, then the scaled face show up, really appreciate it for your suggestion about how to fix it:

below are my code that i use to implement the pinchGesture in my faceView.swift:

func scale(gesture: UIPinchGestureRecognizer){
    if gesture.state == .Changed {
        scale *= gesture.scale
        gesture.scale = 1 
    }
}

in my ViewController.swift:

 @IBOutlet weak var faceView: FaceView! {
    didSet{
        faceView.dataSource = self
faceView.addGestureRecognizer(UIPinchGestureRecognizer(target:faceView,     
action:"scale:"))
    }
}
Solution

  • The problem shouldn't be in your code you pasted, because you know your scaling does work, it just doesn't draw it immediately. I believe you should declare FaceView's scale property with { didSet { setNeedsDisplay() } } to update the UI every time the scale gets changed.

    At this moment, the UI gets updated only when you rotate your device.