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onevcat/TrafficLight.swift

Last active Oct 29, 2020
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Sample of Option Pattern. For my blog post https://onevcat.com/2020/10/use-options-pattern/
//: A UIKit based Playground for presenting user interface
import UIKit
import PlaygroundSupport
public protocol TrafficLightOption {
associatedtype Value
/// 默认的选项值
static var defaultValue: Value { get }
}
extension TrafficLight {
public enum GreenLightColor: TrafficLightOption {
case green
case turquoise
public static let defaultValue: GreenLightColor = .green
}
}
extension TrafficLight {
public var preferredGreenLightColor: TrafficLight.GreenLightColor {
get { self[option: GreenLightColor.self] }
set { self[option: GreenLightColor.self] = newValue }
}
}
public class TrafficLight {
public enum State {
case stop
case proceed
case caution
}
private var options = [ObjectIdentifier: Any]()
public subscript<T: TrafficLightOption>(option type: T.Type) -> T.Value {
get {
options[ObjectIdentifier(type)] as? T.Value
?? type.defaultValue
}
set {
options[ObjectIdentifier(type)] = newValue
}
}
public private(set) var state: State = .stop {
didSet { onStateChanged?(state) }
}
public var onStateChanged: ((State) -> Void)?
public var stopDuration = 4.0
public var proceedDuration = 6.0
public var cautionDuration = 1.5
private var timer: Timer?
public func start() {
guard timer == nil else { return }
turnState(.stop)
}
public func stop() {
timer?.invalidate()
timer = nil
}
private func turnState(_ state: State) {
switch state {
case .proceed:
timer = Timer.scheduledTimer(withTimeInterval: proceedDuration, repeats: false) { _ in
self.turnState(.caution)
}
case .caution:
timer = Timer.scheduledTimer(withTimeInterval: cautionDuration, repeats: false) { _ in
self.turnState(.stop)
}
case .stop:
timer = Timer.scheduledTimer(withTimeInterval: stopDuration, repeats: false) { _ in
self.turnState(.proceed)
}
}
self.state = state
}
}
class MyViewController : UIViewController {
var light: TrafficLight!
override func loadView() {
let view = UIView()
view.backgroundColor = .white
self.view = view
light = TrafficLight()
light.preferredGreenLightColor = .turquoise
light.onStateChanged = { [weak self, weak light] state in
guard let self = self, let light = light else { return }
let color: UIColor
switch state {
case .proceed: color = light.preferredGreenLightColor.color
case .caution: color = .yellow
case .stop: color = .red
}
UIView.animate(withDuration: 0.25) {
self.view.backgroundColor = color
}
}
light.start()
}
deinit {
light.stop()
}
}
extension TrafficLight.GreenLightColor {
var color: UIColor {
switch self {
case .green: return .green
case .turquoise: return UIColor(red: 0.25, green: 0.88, blue: 0.82, alpha: 1.00)
}
}
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()
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