Custom indicator with rotate blink animation like UIActivityIndicatorView - ios

Question

I am trying to make custom activity indicator, see the indicator class below
import UIKit
class MyIndicator: UIView {
let gap = CGFloat(.pi/4 / 6.0)
var count = 0
override func draw(_ rect: CGRect) {
super.draw(rect)
}
func blink() {
backgroundColor = .clear
let duration: CFTimeInterval = 1.2
//let beginTime = CACurrentMediaTime()
let beginTimes: [CFTimeInterval] = [0.25, 1, 1.75, 2.5]
let timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
// Animation
let animation = CAKeyframeAnimation(keyPath: "opacity")
animation.keyTimes = [0, 0.5, 1]
animation.timingFunctions = [timingFunction, timingFunction]
animation.values = [1, 0.3, 1]
animation.duration = duration
animation.repeatCount = HUGE
animation.isRemovedOnCompletion = false
for i in 0...3 {
let shape = CAShapeLayer()
shape.frame = self.bounds
shape.fillColor = UIColor.clear.cgColor
shape.lineWidth = 6.8
shape.strokeColor = UIColor.blue.cgColor
let startAngle:CGFloat = CGFloat(i) * CGFloat(Double.pi/2) + gap
let endAngle:CGFloat = startAngle + CGFloat(Double.pi/2) - gap * 2
shape.path = UIBezierPath(arcCenter: center, radius: -20, startAngle: startAngle, endAngle: endAngle, clockwise: true).cgPath
animation.beginTime = beginTimes[i]
shape.add(animation, forKey: "animation")
self.layer.addSublayer(shape)
}
}
func startAnimating() {
blink()
}
}
let indicator = MyIndicator(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
self.view.addSubview(indicator)
indicator.startAnimating()
I have attached my current result.
But you can see that the animation is not in circular motion like standard UIActivityIndicatorView. Can anyone help me to fix this.

Answer 1

Try using a CAReplicatorLayer and instance delay to get everything in sync. Here is a Playground. I am not 100% sure on the visual you want but this should be close.
//: A UIKit based Playground for presenting user interface
import UIKit
import PlaygroundSupport
class MyIndicator: UIView {
let gap = CGFloat(.pi/4 / 6.0)
private var replicatorLayer = CAReplicatorLayer()
private var mainShapeLayer = CAShapeLayer()
override init(frame: CGRect) {
super.init(frame: frame)
commonSetup()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
commonSetup()
}
func commonSetup(){
mainShapeLayer = CAShapeLayer()
mainShapeLayer.frame = self.bounds
mainShapeLayer.fillColor = UIColor.clear.cgColor
mainShapeLayer.lineWidth = 6.8
mainShapeLayer.strokeColor = UIColor.blue.cgColor
let startAngle:CGFloat = CGFloat(Double.pi * 2) + gap/2
let endAngle:CGFloat = startAngle + CGFloat(Double.pi/2) - gap/2
mainShapeLayer.path = UIBezierPath(arcCenter: center, radius: self.bounds.midX - 10, startAngle: startAngle, endAngle: endAngle, clockwise: true).cgPath
replicatorLayer = CAReplicatorLayer()
replicatorLayer.frame = self.bounds
replicatorLayer.instanceCount = 4
let angle = (Double.pi * 2)/4
replicatorLayer.instanceTransform = CATransform3DRotate(CATransform3DIdentity, CGFloat(angle), 0, 0, 1)
replicatorLayer.addSublayer(mainShapeLayer)
replicatorLayer.opacity = 0
self.layer.addSublayer(replicatorLayer)
}
func animate(){
let defaultDuration : Double = 0.75
let animate = CAKeyframeAnimation(keyPath: "opacity")
animate.values = [1, 0.3, 1]
animate.keyTimes = [0, 0.5, 1]
animate.repeatCount = .greatestFiniteMagnitude
animate.duration = defaultDuration
animate.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
replicatorLayer.instanceDelay = defaultDuration/4
self.mainShapeLayer.add(animate, forKey: nil)
let opacityIn = CABasicAnimation(keyPath: "opacity")
opacityIn.fromValue = 1
opacityIn.toValue = 0
opacityIn.duration = 0.2
replicatorLayer.add(opacityIn, forKey: nil)
self.replicatorLayer.opacity = 1
}
func stopAnimating(){
CATransaction.begin()
let opacityOut = CABasicAnimation(keyPath: "opacity")
opacityOut.fromValue = 1
opacityOut.toValue = 0
opacityOut.duration = 0.2
CATransaction.setCompletionBlock {
[weak self] in
self?.mainShapeLayer.removeAllAnimations()
}
replicatorLayer.add(opacityOut, forKey: nil)
self.replicatorLayer.opacity = 0
CATransaction.commit()
}
override func layoutSubviews() {
super.layoutSubviews()
mainShapeLayer.frame = self.bounds
replicatorLayer.frame = self.bounds
}
}
class MyViewController : UIViewController {
override func loadView() {
let view = UIView()
view.backgroundColor = .white
let indicator = MyIndicator(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
indicator.animate()
//just to simulate starting and stoping
DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 10) {
indicator.stopAnimating()
DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 5) {
indicator.animate()
}
}
view.addSubview(indicator)
self.view = view
}
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()