UIView animation determine center during animation

Question

I\'m using UIView\'s + animateWithDuration:delay:options:animations:completion: method to move my view along a line over the course of a few seconds or so.

Answer 1

I know its too late but maybe it can help somebody else.

CALayer has a presentation() function

func presentation() Returns a copy of the presentation layer object that represents the state of the layer as it currently appears onscreen.

the presentation layer has a frame property what is a CGRect and from here easy the calculate the midpoint.

Demo

The code in swift 3

class ViewController: UIViewController {
        var circle : UIView!
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        let animator = UIViewPropertyAnimator(duration: 10, curve: .easeInOut)
        circle = UIView(frame: CGRect(x: 0.0, y: 0.0, width: 40.0, height: 40.0))
        circle.layer.cornerRadius = 20.0
        circle.backgroundColor = UIColor.blue
        self.view.addSubview(circle)
        Timer.scheduledTimer(withTimeInterval: 0.2, repeats: true)
        {
            [weak self] (myTimer) -> Void in
            if let movingBlueDotFrame = self?.circle.layer.presentation()?.frame
            {
                let blueDotOriginPoint = movingBlueDotFrame.origin
                let blueDotMiddlePoint = CGPoint(x: blueDotOriginPoint.x + movingBlueDotFrame.width/2, y: blueDotOriginPoint.y + movingBlueDotFrame.height/2)
                print(blueDotMiddlePoint)
                if blueDotMiddlePoint == CGPoint(x:100,y:100){
                    print("Yeeaahh")
                    myTimer.invalidate()
                }
            }
       }
        animator.addAnimations {
            self.circle.center = CGPoint(x: 100,y: 100)
        }
        animator.startAnimation()
    }
}