Can't get custom activity indicator to animate - ios

Question

I rewrote a custom activity indicator that was originally in an Objc file into Swift. The activity indicator appears on scene but the animation isn't occurring.
I need some help figuring out why the animation isn't occurring:
vc:
class ViewController: UIViewController {
fileprivate lazy var customActivityView: CustomActivityView = {
let customActivityView = CustomActivityView()
customActivityView.translatesAutoresizingMaskIntoConstraints = false
customActivityView.delegate = self
customActivityView.numberOfCircles = 3
customActivityView.radius = 20
customActivityView.internalSpacing = 3
customActivityView.startAnimating()
return customActivityView
}()
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .white
setAnchors()
}
fileprivate func setAnchors() {
view.addSubview(customActivityView)
customActivityView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
customActivityView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
customActivityView.widthAnchor.constraint(equalToConstant: 100).isActive = true
customActivityView.heightAnchor.constraint(equalToConstant: 100).isActive = true
}
}
extension ViewController: CustomActivityViewDelegate {
func activityIndicatorView(activityIndicatorView: CustomActivityView, circleBackgroundColorAtIndex index: Int) -> UIColor {
let red = CGFloat(Double((arc4random() % 256)) / 255.0)
let green = CGFloat(Double((arc4random() % 256)) / 255.0)
let blue = CGFloat(Double((arc4random() % 256)) / 255.0)
let alpha: CGFloat = 1
return UIColor(red: red, green: green, blue: blue, alpha: alpha)
}
}
Swift file:
import UIKit
protocol CustomActivityViewDelegate: class {
func activityIndicatorView(activityIndicatorView: CustomActivityView, circleBackgroundColorAtIndex index: Int) -> UIColor
}
class CustomActivityView: UIView {
var numberOfCircles: Int = 0
var internalSpacing: CGFloat = 0
var radius: CGFloat = 0
var delay: CGFloat = 0
var duration: CFTimeInterval = 0
var defaultColor = UIColor.systemPink
var isAnimating = false
weak var delegate: CustomActivityViewDelegate?
override init(frame: CGRect) {
super.init(frame: frame)
setupDefaults()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
setupDefaults()
fatalError("init(coder:) has not been implemented")
}
func setupDefaults() {
self.translatesAutoresizingMaskIntoConstraints = false
numberOfCircles = 5
internalSpacing = 5
radius = 10
delay = 0.2
duration = 0.8
}
func createCircleWithRadius(radius: CGFloat, color: UIColor, positionX: CGFloat) -> UIView {
let circle = UIView(frame: CGRect(x: positionX, y: 0, width: radius * 2, height: radius * 2))
circle.backgroundColor = color
circle.layer.cornerRadius = radius
circle.translatesAutoresizingMaskIntoConstraints = false;
return circle
}
func createAnimationWithDuration(duration: CFTimeInterval, delay: CGFloat) -> CABasicAnimation {
let anim: CABasicAnimation = CABasicAnimation(keyPath: "transform.rotation")
anim.fromValue = 0.0
anim.toValue = 1.0
anim.autoreverses = true
anim.duration = duration
anim.isRemovedOnCompletion = false
anim.beginTime = CACurrentMediaTime()+Double(delay)
anim.repeatCount = .infinity
anim.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeInEaseOut)
return anim;
}
func addCircles() {
for i in 0..<numberOfCircles {
var color: UIColor?
color = delegate?.activityIndicatorView(activityIndicatorView: self, circleBackgroundColorAtIndex: i)
let circle = createCircleWithRadius(radius: radius,
color: ((color == nil) ? self.defaultColor : color)!,
positionX: CGFloat(i) * ((2 * self.radius) + self.internalSpacing))
circle.transform = CGAffineTransform(scaleX: 0.5, y: 0.5)
circle.layer.add(self.createAnimationWithDuration(duration: self.duration,
delay: CGFloat(i) * self.delay), forKey: "scale")
self.addSubview(circle)
}
}
func removeCircles() {
self.subviews.forEach({ $0.removeFromSuperview() })
}
#objc func startAnimating() {
if !isAnimating {
addCircles()
self.isHidden = false
isAnimating = true
}
}
#objc func stopAnimating() {
if isAnimating {
removeCircles()
self.isHidden = true
isAnimating = false
}
}
func intrinsicContentSize() -> CGSize {
let width: CGFloat = (CGFloat(self.numberOfCircles) * ((2 * self.radius) + self.internalSpacing)) - self.internalSpacing
let height: CGFloat = radius * 2
return CGSize(width: width, height: height)
}
func setNumberOfCircles(numberOfCircles: Int) {
self.numberOfCircles = numberOfCircles
self.invalidateIntrinsicContentSize()
}
func setRadius(radius: CGFloat) {
self.radius = radius
self.invalidateIntrinsicContentSize()
}
func setInternalSpacing(internalSpacing: CGFloat) {
self.internalSpacing = internalSpacing
self.invalidateIntrinsicContentSize()
}
}

Answer 1

I used the wrong key path for the animation:
I used
// incorrect
let anim: CABasicAnimation = CABasicAnimation(keyPath: "transform.rotation")
but I should've used
// correct
let anim: CABasicAnimation = CABasicAnimation(keyPath: "transform.scale")