Create delay in a block of code in swift 3

Question

The following code doesn't print hello after the delay.

Anything wrong ?

 func delay(seconds delay:Int, closure:@escaping ()->()) {

    DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + .seconds(delay)) {
        closure()
    }
}

delay(seconds: 5) { 
    print("hello")
}

I would try to do it in Xcode, instead of playground. Also, print something in between the lines, to investigate what parts of the functions are running. Besides, Xcode is a little better in telling you what's happening,as opposed to playground. — Farini, May 22 '17 at 16:08
Possible duplicate of [How do I run Asynchronous callbacks in Playground](https://stackoverflow.com/questions/24058336/how-do-i-run-asynchronous-callbacks-in-playground) — Hamish, May 22 '17 at 16:18

score 0 · Answer 1 · answered May 26 '17 at 02:26

I got it working by creating a runloop, otherwise the program just exit without calling the asynchronous block. You shouldn't need this if you are developing for iOS app.

var keepAlive = true

   func delay(seconds delay:Int, closure:@escaping ()->()) {

        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + .seconds(delay)) {
        closure()
        }
    }


   delay(seconds: 5) { 
        print("hello")
        keepAlive = false
    }

let runLoop = RunLoop.current
while keepAlive && runLoop.run(mode: .defaultRunLoopMode, before: Date(timeIntervalSinceNow: 0.1)) {}

score -2 · Answer 2 · answered May 22 '17 at 15:58

-2

let delayInSeconds = 5.0

DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + delayInSeconds) {

print("hello")

}

answered May 22 '17 at 15:58

Alwin

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You can run this in the playground, hello will still not get printed. – Porter Goh May 22 '17 at 16:08
If you are running this in a Playground, you have to include the following two lines: `import PlaygroundSupport` and `PlaygroundPage.current.needsIndefiniteExecution = true` – Dávid Pásztor May 22 '17 at 16:15
thanks, it works. How about running it outside of playground? – Porter Goh May 22 '17 at 16:33
Hey I tell here the basic concept. If you help this then mark as best – Alwin May 22 '17 at 18:08
why I get -1? I think this code is fine. The playground support not mentioned in the question. – Alwin May 22 '17 at 18:12
@Alwin I do not know as well :) my answer got the same -2 without comments – J. Doe May 24 '17 at 12:43
@J.Doe this make me unhappy – Alwin May 24 '17 at 15:16

Create delay in a block of code in swift 3

2 Answers2