I'm having trouble getting this CA animation to work - ios

Question

I'm trying to make an animation where the color red pulses on the screen and when the screen is tapped the speed of the pulse increases. Right now I have two issues. One, is that the animation does not occur, the second is that the animation must speed up without restarting the animation. I want the animation to speed up from whatever point it is at when the screen is tapped.
class ViewController: UIViewController {
var tapCount: Int = 0
var pulseSpeed: Double = 3
let pulseAnimLayer = CALayer()
let pulseAnim = CABasicAnimation(keyPath: "Opacity")
override func viewDidLoad() {
super.viewDidLoad()
counter.center = CGPoint(x: 185, y: 118)
pulseAnim.fromValue = 0.5
pulseAnim.toValue = 1.0
pulseAnim.duration = 3.0
pulseAnim.autoreverses = true
pulseAnim.repeatCount = .greatestFiniteMagnitude
pulseAnimLayer.add(pulseAnim, forKey: "Opacity")
}
func pulseAnimation(pulseSpeed: Double) {
UIView.animate(withDuration: pulseSpeed, delay: 0,
options: [UIViewAnimationOptions.repeat, UIViewAnimationOptions.autoreverse],
animations: {
self.red.alpha = 0.5
self.red.alpha = 1.0
}
)
}
#IBOutlet weak var red: UIImageView!
#IBOutlet weak var counter: UILabel!
#IBAction func screenTapButton(_ sender: UIButton) {
tapCount += 1
counter.text = "\(tapCount)"
pulseSpeed = Double(3) / Double(tapCount)
pulseAnim.duration = pulseSpeed
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
}

Answer 1

I didn't read this carefully enough the first time.
You've got an odd mix here of core animation and UIView animation. The two exist at different levels. Core Animation will allow you to animate a property on a view (say it's background color).
UIView animation is built on top of Core Animation and makes it easier to animate view changes automatically by building the underlying Core Animations.
You start with Core Animation when you create a CABasicAnimation but then you have a function, pulseAnimation which looks to be doing something using UIVIew animations. I think you can get rid of that function entirely.
When you add your CABasicAnimation you tell it to change the value of the layer's "Opacity". What you probably want there is "opacity" (lower case).
Your animation is being applied to a new CALayer that you've created... but you don't seem to ever put that layer into the view (so it is never drawn). More likely than not what you should probably do is attach your animation to the view's layer and just allow that layer to have it's color animated.
To add one layer to another use addSublayer (https://developer.apple.com/reference/quartzcore/calayer/1410833-addsublayer). The view's layer from your code should be available as self.view.layer though you may have to use it in viewWillAppear instead of in viewDidLoad

Answer 2

You need to set the alpha of the red imageview to 0.0 before animating
func pulseAnimation(pulseSpeed: Double) {
UIView.animate(withDuration: pulseSpeed, delay: 1.0,
options: [UIViewAnimationOptions.repeat, UIViewAnimationOptions.autoreverse],
animations: {
self.red.alpha = 0.5
self.red.alpha = 1.0
}
)
}
override func viewDidAppear(_ animated: Bool) {
self.red.alpha = 0.0
counter.center = CGPoint(x: 185, y: 118)
}