取消Swift的定时活动？ [英] Cancel a timed event in Swift?

问题描述

我想在一个事件的10秒钟内运行一段代码，但是我想要取消它，所以如果在这10秒之前发生了一些事情，代码在10秒钟后就不会运行。

我一直在使用，但不可取消：

  static func delay（delay：double，closure：（） - >（））{
 dispatch_after（
 dispatch_time（
 DISPATCH_TIME_NOW，
 Int64（delay * Double（NSEC_PER_SEC） ）
），
 dispatch_get_main_queue（），关闭
）
} 
  

如何完成这个？

解决方案

尝试这个（Swift 2.x，见下面的David的答案Swift 3）：

  typealias dispatch_cancelable_closure =（cancel：Bool） - > （）
 
 func delay（time：NSTimeInterval，closure：（） - >（）） - > dispatch_cancelable_closure？ （
 dispatch_time（
 DISPATCH_TIME_NOW，
 Int64（时间*双） （NSEC_PER_SEC））
），
 dispatch_get_main_queue（），clsr）
} 
 
 var closure：dispatch_block_t？ = closure 
 var cancelableClosure：dispatch_cancelable_closure？ 
 
 let delayedClosure：dispatch_cancelable_closure = {cancel in 
 if let clsr = closure {
 if（cancel == false）{
 dispatch_async（dispatch_get_main_queue（），clsr） ; 
} 
} 
 closure = nil 
 cancelableClosure = nil 
} 
 
 cancelableClosure = delayedClosure 
 
 dispatch_later { 
如果让delayedClosure = cancelableClosure {
 delayedClosure（cancel：false）
} 
} 
 
 return cancelableClosure; 
} 
 
 func cancel_delay（closure：dispatch_cancelable_closure？）{
如果闭合！= nil {
 closure！（cancel：true）
} 
 
 
 //使用
 let retVal = delay（2.0）{
 println（Later）
} 
 delay（1.0）{ 
 cancel_delay（retVal）
} 
  

来自Waam的评论： dispatch_after - GCD in swift？

I want to run a block of code in 10 seconds from an event, but I want to be able to cancel it so that if something happens before those 10 seconds, the code won't run after 10 seconds have gone by.

I've been using this, but it's not cancellable:

static func delay(delay:Double, closure:()->()) {
  dispatch_after(
    dispatch_time(
      DISPATCH_TIME_NOW,
      Int64(delay * Double(NSEC_PER_SEC))
    ),
    dispatch_get_main_queue(), closure
  )
}

How can I accomplish this?

解决方案

Try this (Swift 2.x, see David's answer below for Swift 3):

typealias dispatch_cancelable_closure = (cancel : Bool) -> ()

func delay(time:NSTimeInterval, closure:()->()) ->  dispatch_cancelable_closure? {

    func dispatch_later(clsr:()->()) {
        dispatch_after(
            dispatch_time(
                DISPATCH_TIME_NOW,
                Int64(time * Double(NSEC_PER_SEC))
            ),
            dispatch_get_main_queue(), clsr)
    }

    var closure:dispatch_block_t? = closure
    var cancelableClosure:dispatch_cancelable_closure?

    let delayedClosure:dispatch_cancelable_closure = { cancel in
        if let clsr = closure {
            if (cancel == false) {
                dispatch_async(dispatch_get_main_queue(), clsr);
            }
        }
        closure = nil
        cancelableClosure = nil
    }

    cancelableClosure = delayedClosure

    dispatch_later {
        if let delayedClosure = cancelableClosure {
            delayedClosure(cancel: false)
        }
    }

    return cancelableClosure;
}

func cancel_delay(closure:dispatch_cancelable_closure?) {
    if closure != nil {
        closure!(cancel: true)
    }
}

// usage
let retVal = delay(2.0) {
    println("Later")
}
delay(1.0) {
    cancel_delay(retVal)
}

From Waam's comment here: dispatch_after - GCD in swift?

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