debounce 与 throttle 高阶函数简易实现以及演示两者区别

debouncing_and_throttling.playground.swift

//: 理解 Debouncing 与 Throttling 的区别

import Cocoa
import PlaygroundSupport

typealias Action = () -> ()

func debounce(threshold: TimeInterval, action: @escaping Action) -> Action {
    var timer: DispatchSourceTimer?
    return {
        if timer != nil {
            timer!.cancel()
        }
        
        timer = DispatchSource.makeTimerSource()
        timer!.setEventHandler {
            action()
        }
        
        timer!.scheduleOneshot(deadline: .now() + .milliseconds(Int(threshold * 1000)))
        timer!.activate()
    }
}

func throttle(threshold: TimeInterval, action: @escaping Action) -> Action {
    var last: CFAbsoluteTime = 0
    return {
        let current = CFAbsoluteTimeGetCurrent();
        if current >= last + threshold {
            action()
            last = current
        }
    }
}


class TestCase {
    
    let throttledFunc = throttle(threshold: 0.5) {
        print("Throttle button clicked!")
    }
    
    let debouncedFunc = debounce(threshold: 0.5) {
        print("Debounce button clicked!")
    }
    
    @objc func testThrottle() {
        throttledFunc()
    }
    
    @objc func testDebounce() {
        debouncedFunc()
    }
    
}

let test = TestCase()

let throttleButton = NSButton.init(title: "Throttle", target: test, action: #selector(TestCase.testThrottle))
let debounceButton = NSButton.init(title: "Debounce", target: test, action: #selector(TestCase.testDebounce))

let view = NSStackView(views: [throttleButton, debounceButton])
view.orientation = .vertical
view.frame = NSMakeRect(0, 0, 100, 100)

PlaygroundPage.current.liveView = view