How to program a delay in Swift 3
After a lot of research, I finally figured this one out.
DispatchQueue.main.asyncAfter(deadline: .now() + 2.0) { // Change `2.0` to the desired number of seconds. // Code you want to be delayed}
This creates the desired "wait" effect in Swift 3 and Swift 4.
Inspired by a part of this answer.
I like one-line notation for GCD, it's more elegant:
DispatchQueue.main.asyncAfter(deadline: .now() + 42.0) { // do stuff 42 seconds later }
Also, in iOS 10 we have new Timer methods, e.g. block initializer:
(so delayed action may be canceled)
let timer = Timer.scheduledTimer(withTimeInterval: 42.0, repeats: false) { (timer) in // do stuff 42 seconds later }
Btw, keep in mind: by default, timer is added to the default run loop mode. It means timer may be frozen when the user is interacting with the UI of your app (for example, when scrolling a UIScrollView)You can solve this issue by adding the timer to the specific run loop mode:
RunLoop.current.add(timer, forMode: .common)
At this blog post you can find more details.
Try the following function implemented in Swift 3.0 and above
func delayWithSeconds(_ seconds: Double, completion: @escaping () -> ()) { DispatchQueue.main.asyncAfter(deadline: .now() + seconds) { completion() }}
Usage
delayWithSeconds(1) { //Do something}