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//
// SpinnerActivityIndicatorView.swift
// MullvadVPN
//
// Created by pronebird on 15/05/2019.
// Copyright © 2019 Mullvad VPN AB. All rights reserved.
//
import UIKit
private let kRotationAnimationKey = "rotation"
private let kAnimationDuration = 0.6
class SpinnerActivityIndicatorView: UIView {
enum Style {
case small, medium, large
var intrinsicSize: CGSize {
switch self {
case .small:
return .init(width: 16, height: 16)
case .medium:
return .init(width: 20, height: 20)
case .large:
return .init(width: 60, height: 60)
}
}
}
private let imageView = UIImageView(image: UIImage(named: "IconSpinner"))
private(set) var isAnimating = false
private(set) var style = Style.large
private var startTime = CFTimeInterval(0)
private var stopTime = CFTimeInterval(0)
override var intrinsicContentSize: CGSize {
return style.intrinsicSize
}
init(style: Style) {
self.style = style
super.init(frame: CGRect(origin: .zero, size: style.intrinsicSize))
addSubview(imageView)
isHidden = true
backgroundColor = UIColor.clear
NotificationCenter.default.addObserver(
self,
selector: #selector(restartAnimationIfNeeded),
name: UIApplication.willEnterForegroundNotification,
object: nil
)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func didMoveToWindow() {
super.didMoveToWindow()
if window != nil {
restartAnimationIfNeeded()
}
}
override func layoutSubviews() {
super.layoutSubviews()
imageView.frame = CGRect(origin: .zero, size: style.intrinsicSize)
}
func startAnimating() {
guard !isAnimating else { return }
isAnimating = true
isHidden = false
addAnimation()
}
func stopAnimating() {
guard isAnimating else { return }
isAnimating = false
isHidden = true
removeAnimation()
}
private func addAnimation() {
let timeOffset = stopTime - startTime
let anim = animation()
anim.timeOffset = timeOffset
layer.add(anim, forKey: kRotationAnimationKey)
startTime = layer.convertTime(CACurrentMediaTime(), from: nil) - timeOffset
}
private func removeAnimation() {
layer.removeAnimation(forKey: kRotationAnimationKey)
stopTime = layer.convertTime(CACurrentMediaTime(), from: nil)
}
@objc private func restartAnimationIfNeeded() {
let anim = layer.animation(forKey: kRotationAnimationKey)
if isAnimating && anim == nil {
removeAnimation()
addAnimation()
}
}
private func animation() -> CABasicAnimation {
let animation = CABasicAnimation(keyPath: "transform.rotation")
animation.toValue = NSNumber(value: Double.pi * 2)
animation.duration = kAnimationDuration
animation.repeatCount = Float.infinity
animation.timingFunction = CAMediaTimingFunction(name: .linear)
return animation
}
}
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