在使用 RxSwift 的工程中，没有发现倒计时的功能，于是自己实现了一个：
/// 倒计时
/// - Parameters:
/// - second: 倒计时的秒数
/// - immediately: 是否立即开始，true 时将立即开始倒计时，false 时将在 1 秒之后开始倒计时
/// - duration: 倒计时的过程
/// - Returns: 倒计时结束时的通知
func countdown(second: Int,
immediately: Bool = true,
duration: ((Int) -> Void)?) -> Single<Void> {
guard second > 0 else {
return Single<Void>.just(())
}
if immediately {
duration?(second)
}
return Observable<Int>
.interval(RxTimeInterval.seconds(1), scheduler: MainScheduler.instance)
.map { second - (immediately ? ($0 + 1) : $0) }
.take(second + (immediately ? 0 : 1))
.do(onNext: { (index) in
duration?(index)
})
.filter { return $0 == 0 }
.map { _ in return () }
.asSingle()
}
使用的方法为：
debugPrint(Date())
countdown(second: 5) { (index) in
debugPrint(Date())
debugPrint("倒计时：\(index)")
}
.subscribe(onSuccess: { () in
debugPrint(Date())
debugPrint("倒计时结束")
}) { (error) in
debugPrint("倒计时错误:\(error)")
}
.disposed(by: disposeBag)
输出：
2020-09-08 08:58:06 +0000
2020-09-08 08:58:06 +0000
"倒计时：5"
2020-09-08 08:58:07 +0000
"倒计时：4"
2020-09-08 08:58:08 +0000
"倒计时：3"
2020-09-08 08:58:09 +0000
"倒计时：2"
2020-09-08 08:58:10 +0000
"倒计时：1"
2020-09-08 08:58:11 +0000
"倒计时：0"
2020-09-08 08:58:11 +0000
"倒计时结束"
