How to sleep for few milliseconds in swift 2.2?

please anyone tell me how to use sleep() for few milliseconds in swift 2.2?

while (true){
print("sleep for 0.002 seconds.")
sleep(0.002) // not working
}

but

while (true){
print("sleep for 2 seconds.")
sleep(2) // working
}

it is working.

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use func usleep(_: useconds_t) -> Int32 (import Darwin or Foundation ...)

IMPORTANT: usleep() takes millionths of a second, so usleep(1000000) will sleep for 1 sec

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If you really need to sleep, try usleepas suggested in @user3441734's answer.

However, you may wish to consider whether sleep is the best option: it is like a pause button, and the app will be frozen and unresponsive while it is running.

You may wish to use NSTimer.

 //Declare the timer
var timer = NSTimer.scheduledTimerWithTimeInterval(0.002, target: self, selector: #selector(MyClass.update), userInfo: nil, repeats: true)
self, selector: "update", userInfo: nil, repeats: true)






func update() {
// Code here
}

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最佳答案

usleep() takes millionths of a second

usleep(1000000) //will sleep for 1 second
usleep(2000) //will sleep for .002 seconds

 let ms = 1000
usleep(useconds_t(2 * ms)) //will sleep for 2 milliseconds (.002 seconds)

let second: Double = 1000000
usleep(useconds_t(0.002 * second)) //will sleep for 2 milliseconds (.002 seconds)

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Alternatively:

DispatchQueue.main.asyncAfter(deadline: .now() + 0.002) {
/*Do something after 0.002 seconds have passed*/
}

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Non-blocking solution for usleep:

DispatchQueue.global(qos: .background).async {
let second: Double = 1000000
usleep(useconds_t(0.002 * second))
print("Active after 0.002 sec, and doesn't block main")
DispatchQueue.main.async{
//do stuff in the main thread here
}
}

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I think more elegant than usleep solution in current swift syntax is:

Thread.sleep(forTimeInterval: 0.002)

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For Example Change Button Alpha Value

 sender.alpha = 0.5
 

DispatchQueue.main.asyncAfter(deadline:.now() + 0.2){
sender.alpha = 1.0
}