CODEWITHSUNDEEP
swiftuikitsleep
sulabh qg
sulabh qg

Reputation: 1235

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.

Upvotes: 93

Views: 79277

Answers (7)

ugurpolat
ugurpolat

Reputation: 11

For Example Change Button Alpha Value

 sender.alpha = 0.5
 
 DispatchQueue.main.asyncAfter(deadline:.now() + 0.2){
             sender.alpha = 1.0
         }

Upvotes: 0

Phil Dukhov
Phil Dukhov

Reputation: 87914

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

Thread.sleep(forTimeInterval: 0.002)

Upvotes: 25

user3441734
user3441734

Reputation: 17544

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

Upvotes: 11

Sentry.co
Sentry.co

Reputation: 5569

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
    }
}

Upvotes: 4

Sentry.co
Sentry.co

Reputation: 5569

Alternatively:

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

Upvotes: 2

Elijah
Elijah

Reputation: 8610

usleep() takes millionths of a second

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

OR

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

OR

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

Upvotes: 160

rocket101
rocket101

Reputation: 7537

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
}

Upvotes: 4

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