swift 倒计时功能(粘贴复制就能使用)

首先在项目中进入RxCocoa 和RxSwift

import RxCocoa
import RxSwift

声明需要的属性

let disposed = DisposeBag()
let timer = Observable<Int>.interval(1, scheduler: MainScheduler.instance)
let countDownStopped = Variable(true)
let leftTime = Variable(Int(30))

懒加载button和label,之后再加载view的时候先使lable隐藏，button展示

leftLabel.isHidden = true
barBtn.isHidden = false

view.addSubview(barBtn)
view.addSubview(leftLabel)

这里就是最重要的方法，在点击button的时候调用这个方法就实现了

func startClicked() {
        leftLabel.isHidden = false
        barBtn.isHidden = true
        self.countDownStopped.value = false
            timer.takeUntil(countDownStopped.asObservable().filter{$0})
            .subscribe(onNext: { [weak self](event) in
                self!.leftTime.value -= 1
                print("这里是剩余的时间:\(self?.leftTime.value ?? 0)")
                self?.leftLabel.text = "这里是剩余的时间:\(self?.leftTime.value ?? 0)秒"
                if (self!.leftTime.value == 0) {
                    print("倒计时结束")
                    self!.countDownStopped.value = true
                    self!.leftTime.value = 30
                    self!.leftLabel.isHidden = true
                    self!.barBtn.isHidden = false
                    self?.leftLabel.text = "这里是剩余的时间:\(self?.leftTime.value ?? 0)秒"
                }
            }, onError: { (error) in


            }).disposed(by: disposed)
    }