How to animate object using bezier path? - ios

Question

Here is my code to draw dashed line
func drawLine() {
let shapeLayer = CAShapeLayer()
shapeLayer.bounds = viewDraw.bounds
shapeLayer.position = CGPoint(x: viewDraw.bounds.width/2, y: viewDraw.bounds.height/2)
shapeLayer.fillColor = nil
shapeLayer.strokeColor = ColorConstants.ThemeColor.cgColor
shapeLayer.lineWidth = 3
shapeLayer.lineJoin = CAShapeLayerLineJoin.round // Updated in swift 4.2
shapeLayer.lineDashPattern = [10]
let path = UIBezierPath(roundedRect: viewDraw.bounds, cornerRadius: viewDraw.bounds.size.height/2)
shapeLayer.path = path.cgPath
viewDraw.layer.addSublayer(shapeLayer)
let animation = CABasicAnimation(keyPath: "strokeEnd")
animation.fromValue = 0
animation.duration = 1
shapeLayer.add(animation, forKey: "MyAnimation")
}
Now as per my screenshot I want to animate blue dot to red dot within that dashed line infinite time. When blue dot reaches red dot then it will start again with blue dot points.
Note: This whole screen is dynamic so, Line draw is also dynamic according to screen height
Any help would be appreciated

Answer 1

You are almost there
Now you have to add animation using CAKeyframeAnimation which has property path where you can pass the path where you want to animate
here is working sample code
func drawLine() {
let shapeLayer = CAShapeLayer()
shapeLayer.bounds = self.view.bounds
shapeLayer.position = CGPoint(x: self.view.bounds.width/2, y: self.view.bounds.height/2)
shapeLayer.fillColor = nil
shapeLayer.strokeColor = UIColor.red.cgColor
shapeLayer.lineWidth = 3
shapeLayer.lineJoin = CAShapeLayerLineJoin.round // Updated in swift 4.2
shapeLayer.lineDashPattern = [10]
let path = UIBezierPath(roundedRect: self.view.bounds, cornerRadius: self.view.bounds.size.height/2)
shapeLayer.path = path.cgPath
self.view.layer.addSublayer(shapeLayer)
let animation1 = CABasicAnimation(keyPath: "strokeEnd")
animation1.fromValue = 0
animation1.duration = 1
shapeLayer.add(animation1, forKey: "MyAnimation")
// Create squareView and add animation
let animation = CAKeyframeAnimation(keyPath: #keyPath(CALayer.position))
animation.duration = 1
animation.repeatCount = MAXFLOAT
animation.path = path.cgPath
let squareView = UIView()
// Don't worry about x,y and width and height it will not affect the animation
squareView.frame = CGRect(x: 0, y: 0, width: 50, height: 50)
squareView.backgroundColor = .lightGray
view.addSubview(squareView)
// You can also pass any unique string value for key
squareView.layer.add(animation, forKey: nil)
}
You can see this tutorial for more help http://mathewsanders.com/animations-in-swift-part-two/