如何在swift中为NSTimer设置超时？

Question

我有一个NSTimer对象如下:

 var timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: "updateTimer", userInfo: nil, repeats: true)

我想把超时给我的计时器.也许你知道android中的postdelayed方法.我想要同样的东西的快速版本.我怎样才能做到这一点 ？

Answer 1

NSTimer不适合可变间隔时间.您可以使用一个指定的延迟时间进行设置,但无法对其进行更改.比NSTimer每次停止和启动更优雅的解决方案是使用dispatch_after.

借用马特的答案:

// this makes a playground work with GCD
XCPlaygroundPage.currentPage.needsIndefiniteExecution = true

struct DispatchUtils {

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


class Alpha {

    // some delay time
    var currentDelay : NSTimeInterval = 2

    // a delayed function
    func delayThis() {

        // use this instead of NSTimer
        DispatchUtils.delay(currentDelay) {
            print(NSDate())
            // do stuffs

            // change delay for the next pass
            self.currentDelay += 1

            // call function again
            self.delayThis()
        }
    }
}

let a = Alpha()

a.delayThis()

在操场上试试吧.它将对函数的每次传递应用不同的延迟.