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//
// SpinnerActivityIndicatorView.swift
// MullvadVPN
//
// Created by pronebird on 15/05/2019.
// Copyright © 2019 Amagicom AB. All rights reserved.
//
import UIKit
private let kRotationAnimationKey = "rotation"
private let kAnimationDuration = 0.6
@IBDesignable class SpinnerActivityIndicatorView: UIView {
/// Thickness of the front and back circles
var thickness: CGFloat = 6 {
didSet {
setLayersThickness()
}
}
/// The back circle color
var backCircleColor = UIColor.white.withAlphaComponent(0.2) {
didSet {
setBackCircleLayerColor()
}
}
/// The front circle color
var frontCircleColor: UIColor? {
didSet {
setFrontCircleLayerColor()
}
}
@IBInspectable var isAnimating: Bool = false {
didSet {
guard oldValue != isAnimating else { return }
if isAnimating {
startAnimating()
} else {
stopAnimating()
}
}
}
fileprivate let frontCircle = CAShapeLayer()
fileprivate let backCircle = CAShapeLayer()
fileprivate var startTime = CFTimeInterval(0)
fileprivate var stopTime = CFTimeInterval(0)
override var intrinsicContentSize: CGSize {
return CGSize(width: 48, height: 48)
}
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
commonInit()
}
deinit {
unregisterFromAppStateNotifications()
}
override func layoutSublayers(of layer: CALayer) {
super.layoutSublayers(of: layer)
setupBezierPaths()
}
override func didMoveToWindow() {
super.didMoveToWindow()
if window != nil {
restartAnimationIfNeeded()
}
}
override func tintColorDidChange() {
super.tintColorDidChange()
setFrontCircleLayerColor()
}
// MARK: - Private
private func startAnimating() {
isHidden = false
addAnimation()
}
private func stopAnimating() {
isHidden = true
removeAnimation()
}
private func commonInit() {
registerForAppStateNotifications()
isHidden = true
backgroundColor = UIColor.clear
backCircle.fillColor = UIColor.clear.cgColor
frontCircle.fillColor = UIColor.clear.cgColor
frontCircle.lineCap = .round
setBackCircleLayerColor()
setFrontCircleLayerColor()
setLayersThickness()
layer.addSublayer(backCircle)
layer.addSublayer(frontCircle)
}
private func setLayersThickness() {
backCircle.lineWidth = thickness
frontCircle.lineWidth = thickness
}
private func setBackCircleLayerColor() {
backCircle.strokeColor = backCircleColor.cgColor
}
private func setFrontCircleLayerColor() {
frontCircle.strokeColor = frontCircleColor?.cgColor ?? tintColor.cgColor
}
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 registerForAppStateNotifications() {
NotificationCenter.default.addObserver(self, selector: #selector(restartAnimationIfNeeded), name: UIApplication.willEnterForegroundNotification, object: nil)
}
private func unregisterFromAppStateNotifications() {
NotificationCenter.default.removeObserver(self)
}
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
}
private func setupBezierPaths() {
let center = CGPoint(x: bounds.size.width * 0.5, y: bounds.size.height * 0.5)
let radius = bounds.size.width * 0.5 - thickness
let closedRingPath = UIBezierPath(arcCenter: center, radius: radius, startAngle: 0, endAngle: CGFloat.pi * 2, clockwise: true)
let openRingPath = UIBezierPath(arcCenter: center, radius: radius, startAngle: 0, endAngle: CGFloat.pi * 1.5, clockwise: true)
backCircle.path = closedRingPath.cgPath
frontCircle.path = openRingPath.cgPath
}
}
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