Swift sleep function

In swift, sleep is going to block the main thread and make the app unresponsive... You can use NSTimer but the fire time is not that accurate... I prefer:

let seconds = 3.0
let delay = seconds * Double(NSEC_PER_SEC)
let dispatchTime = dispatch_time(DISPATCH_TIME_NOW, Int64(delay))
dispatch_after(dispatchTime, dispatch_get_main_queue(), {
     // code to be executed after the delay
})