Creating a UIView with PanGestureRecognizer and activating it without lifting the finger - ios

Question

I've created a circle on the screen by creating a UIView at the finger's location when touchesBegan():
In ViewController:
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
for touch in touches {
let pos = touch.locationInView(view)
let radius: CGFloat = touch.majorRadius * 2
let circleView = CircleView(frame: CGRectMake(pos.x - radius / 2, pos.y - radius / 2, radius, radius))
view.addSubview(circleView)
}
}
In CircleView:
override init(frame: CGRect) {
super.init(frame: frame)
let recognizer = UIPanGestureRecognizer(target: self, action: Selector("handlePan:"))
recognizer.delegate = self
self.addGestureRecognizer(recognizer)
}
This creates the circle, but does not move it immediately when I move my finger. Instead, I have to pick my finger up and place it back on the circle before handlePan() kicks in.
Is there a way to start tracking a pan gesture without lifting the finger that spawned it's parent view, taking into account there may be multiple fingers touching and moving around the screen?

Answer 1

The issue here is that you're using both touchesBegan, and a UIPanGestureRecognizer. For best results, use one or the other. If you're going to do it with just a pan gesture (which is what I would do), do the following:
func handlePan(gesture: UIPanGestureRecognizer) {
if gesture.state == UIGestureRecognizerState.Began {
//handle creating circle
} else if gesture.state == UIGestureRecognizerState.Changed {
//handle movement
}
}
Hope this helps!

Answer 2

If you have already created the circle view successfully in method touchesBegan:withEvent:
you can
Make that circle view a property
Move that circle view directly in method touchesMoved:withEvent:
This won't require you pick your finger up first

Answer 3

I was able to accomplish multiple independent touches by keeping a dictionary of all active touches and creating the circle views in touchesBegan() and updating their position in touchesMoved() by querying that dictionary.
var fingerTouches = [UITouch: CircleView]()
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
for touch in touches {
let pos = touch.locationInView(view)
let radius: CGFloat = touch.majorRadius * 2
let circle = CircleView(frame: CGRectMake(pos.x - radius / 2, pos.y - radius / 2, radius, radius))
view.addSubview(circle)
fingerTouches[touch] = circle
}
}
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
for touch in touches {
let pos = touch.locationInView(view)
let radius: CGFloat = touch.majorRadius * 2
fingerTouches[touch]!.frame = CGRectMake(pos.x - radius / 2, pos.y - radius / 2, radius, radius)
}
}
override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
for touch in touches {
fingerTouches[touch]!.removeFromSuperview()
}
}