编码1蜜蜂采蜜

一朵花有Open和Close两种状态，3只蜜蜂在花Open的时候去采蜜，在花Close的时候回巢，用面向对象技术和Design Pattern方法模拟上面过程，输出如下:

Flower openBee 1's eating time!Bee 2's eating time!Bee 3's eating time!Floer closeBee 1's bed time!Bee 2's bed time!Bee 3's bed time!

编码实现上述情景，要求使用一种Design Pattern方法，使花和蜜蜂之间松耦合。

protocol ObserverProtocol {    var id: Int {get set}    func onValueChanged(_ value: Any?)}protocol ObservableProtocol: class {    var observers: [ObserverProtocol] {get set}    func addObserver(_ observer: ObserverProtocol)    func removeObserver(_ observer: ObserverProtocol)    func notifyObservers(_ observers: [ObserverProtocol])}class Observable<T>: ObservableProtocol {    var value: T {        didSet {            self.notifyObservers(self.observers)        }    }        internal var observers: [ObserverProtocol] = []        init(value: T) {        self.value = value    }        func addObserver(_ observer: ObserverProtocol) {        guard self.observers.contains(where: { $0.id == observer.id}) == false else {            return        }        self.observers.append(observer)    }        func removeObserver(_ observer: ObserverProtocol) {        guard let index = self.observers.firstIndex(where: { $0.id == observer.id}) else {            return        }        self.observers.remove(at: index)    }        func notifyObservers(_ observers: [ObserverProtocol]) {        observers.forEach({$0.onValueChanged(value)})    }        deinit {        observers.removeAll()    }}enum FlowerStatus: String {    case open = "Flower open"    case close = "Flower close"}class Flower: Observable<FlowerStatus> {    var status: FlowerStatus {        get {            return self.value        }        set {            print(newValue.rawValue)            self.value = newValue        }    }}struct Bee: ObserverProtocol {    var id: Int    var name: String    func onValueChanged(_ value: Any?) {        if let status = value as? FlowerStatus {            if status == .open {                print("\(name)'s eating time!")            } else {                print("\(name)'s beding time!")            }        }    }}func beeTime() {    let flower = Flower(value: .close)    let bee1 = Bee.init(id: 1, name: "Bee 1")    let bee2 = Bee.init(id: 2, name: "Bee 2")    let bee3 = Bee.init(id: 3, name: "Bee 3")    flower.addObserver(bee1)    flower.addObserver(bee2)    flower.addObserver(bee3)        flower.status = .open    flower.status = .close}beeTime()

Observable另一种实现，注意，这种方法实现，打印是无序的

class Observable<T> {    typealias CompletionHandler = ((T) -> Void)        var value: T {        didSet {            self.notifyObservers(self.observers)        }    }        var observers: [Int: CompletionHandler] = [:]        init(value: T) {        self.value = value    }        func addObserver(_ observer: ObserverProtocol, completion: @escaping CompletionHandler) {        self.observers[observer.id] = completion    }        func removeObserver(_ observer: ObserverProtocol) {        self.observers.removeValue(forKey: observer.id)    }        func notifyObservers(_ observer: [Int: CompletionHandler]) {        observers.forEach({$0.value(value)})    }        deinit {        observers.removeAll()    }}func beeTime() {    let flower = Flower(value: .close)        let bee1 = Bee.init(id: 1, name: "Bee 1")    let bee2 = Bee.init(id: 2, name: "Bee 2")    let bee3 = Bee.init(id: 3, name: "Bee 3")    flower.addObserver(bee1) { (status) in        if status == .open {            print("\(bee1.name)'s eating time!")        } else {            print("\(bee1.name)'s beding time!")        }    }        flower.addObserver(bee2) { (status) in        if status == .open {            print("\(bee2.name)'s eating time!")        } else {            print("\(bee2.name)'s beding time!")        }    }        flower.addObserver(bee3) { (status) in        if status == .open {            print("\(bee3.name)'s eating time!")        } else {            print("\(bee3.name)'s beding time!")        }    }    flower.status = .open    flower.status = .close}beeTime()