它应能正常工作...在这种情况下，只需使用它即可！

It works as it should ... In that case, just use it!

嗯...但是如何使用呢?实际上，它不是非常灵活，尤其是在编译器声明不支持多个属性包装器"之前:-)

Hm ... but how to use it? In reality, it is not very flexible, especially till compiler claims "Multiple property wrappers are not supported" :-)

如果您的目标是在UIKit或SwiftUI应用中使用它，我建议您使用其他方法.

If your goal is to use it in UIKit or SwiftUI app, I suggest you different approach.

让我们尝试一些简约但可以正常工作的SwiftUI示例

Lets try some minimalistic, but fully working SwiftUI example

//
//  ContentView.swift
//  tmp031
//
//  Created by Ivo Vacek on 26/01/2020.
//  Copyright © 2020 Ivo Vacek. NO rights reserved.
//

import SwiftUI
import Combine

class S: ObservableObject {
    @Published var text: String = ""
    @Published var debouncedText: String = ""

    private var store = Set<AnyCancellable>()
    init(delay: Double) {
        $text
            .debounce(for: .seconds(delay), scheduler: RunLoop.main)
            .sink { [weak self] (s) in
            self?.debouncedText = s
        }.store(in: &store)
    }
}

struct ContentView: View {
    @ObservedObject var model = S(delay: 2)
    var body: some View {
        List {
            Color.clear
            Section(header: Text("Direct")) {
                Text(model.text).font(.title)
            }
            Section(header: Text("Debounced")) {
                Text(model.debouncedText).font(.title)
            }
            Section(header: Text("Source")) {
                TextField("type here", text: $model.text).font(.title)
            }

        }
    }
}


struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

您仍然可以根据需要多次订阅发布者model.$debouncedText.而且，如果您希望使用自己的动作来执行操作，也没问题！

You still can subscribe to model.$debouncedText which is Publisher as many times, as you need. And if you like to use your own action to be performed, no problem as well!

model.$debouncedText
    .sink { (s) in
        doSomethingWithDebouncedValue(s)
    }

示例应用用法

更新:如果您无法使用Combine，但是喜欢类似的语法... 首先定义协议

UPDATE: if you not able to use Combine, but you like similar syntax ... First define the protokol

protocol Debounce: class {
    associatedtype Value: Hashable
    var _value: Value { get set }
    var _completions: [(Value)->Void] { get set}
    var _delay: TimeInterval { get set }
    var _dw: DispatchWorkItem! { get set }
    func debounce(completion: @escaping (Value)->Void)
}

和防抖功能的默认实现.这个想法是，与在Combine上使用.publisher.sink()相同的方式来使用防抖动. _debounce是反跳功能的内部"实现.它比较当前和延迟"的旧值，如果它们相等，则执行此操作.

and default implementation of debounce function. The idea is, to use debounce the same way, as .publisher.sink() on Combine. _debounce is "internal" implementation of debouncing functionality. It compare current and "delay" old value and if they are equal, do the job.

extension Debounce {
    func debounce(completion: @escaping (Value)->Void) {
        _completions.append(completion)
    }
    func _debounce(newValue: Value, delay: TimeInterval, completions:  [(Value)->Void]) {
        if _dw != nil {
            _dw.cancel()
        }
        var dw: DispatchWorkItem!
        dw = DispatchWorkItem(block: { [weak self, newValue, completions] in
            if let s = self, s._value == newValue {
                for completion in completions {
                    completion(s._value)
                }
            }
            dw = nil
        })
        _dw = dw
        DispatchQueue.main.asyncAfter(deadline: .now() + delay, execute: dw)
    }
}

现在，我们有了属性包装器的所有组件.

Now we have all componets of our property wrapper.

@propertyWrapper class Debounced<T: Hashable> {

    final class Debouncer: Debounce {
        typealias Value = T

        var _completions: [(T) -> Void] = []
        var _delay: TimeInterval
        var _value: T {
            willSet {
                _debounce(newValue: newValue, delay: _delay, completions: _completions)
            }
        }
        var _dw: DispatchWorkItem!
        init(_value: T, _delay: TimeInterval) {
            self._value = _value
            self._delay = _delay
        }
    }

    var wrappedValue: T {
        get { projectedValue._value }
        set { projectedValue._value = newValue }
    }

    var projectedValue: Debouncer

    init(wrappedValue: T, delay: TimeInterval) {
        projectedValue = Debouncer(_value: wrappedValue, _delay: delay)
    }
    deinit {
        print("deinit")
    }
}

让我们尝试一下

do {
    struct S {
        @Debounced(delay: 0.2) var value: Int = 0
    }

    let s = S()
    print(Date(), s.value, "initial")

    s.$value.debounce { (i) in
        print(Date(), i, "debounced A")
    }

    s.$value.debounce { (i) in
        print(Date(), i, "debounced B")
    }

    var t = 0.0
    (0 ... 8).forEach { (i) in
        let dt = Double.random(in: 0.0 ... 0.6)
        t += dt
        DispatchQueue.main.asyncAfter(deadline: .now() + t) { [t] in
            s.value = i
            print(s.value, t)
        }
    }
}

打印类似

2020-02-04 09:53:11 +0000 0 initial
0 0.46608517831539165
2020-02-04 09:53:12 +0000 0 debounced A
2020-02-04 09:53:12 +0000 0 debounced B
1 0.97078412234771
2 1.1756938500918692
3 1.236562020385944
4 1.4076127046937024
2020-02-04 09:53:13 +0000 4 debounced A
2020-02-04 09:53:13 +0000 4 debounced B
5 1.9313412744029004
6 2.1617775513150366
2020-02-04 09:53:14 +0000 6 debounced A
2020-02-04 09:53:14 +0000 6 debounced B
7 2.6665465865810205
8 2.9287734023206418
deinit