I have doubt for the run thread with time delay Dispatch is not enter to after finished the time?
for i in 0...10000 {
let deadLine = DispatchTime.now() + .milliseconds(1000)
DispatchQueue.main.asyncAfter(deadline: deadLine) {
print(i)
}
}
Anyone have done this before? Thanks.
The for loop doesn't wait, it is executed in the main thread. DispatchQueue.main.asyncAfter doesn't block the main thread, all it does is queue a block of code to be executed after certain time. Queuing the printing of i is done at almost the same time, maybe spaced in time by a few microseconds if not nanoseconds.
Instead of trying to block the main thread, you could use the Timer API :
//In a playground
var timer: Timer? = nil
var counter = 0
timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { _ in
print("\(counter)\t\(Date())")
if counter == 10 {
timer?.invalidate()
}
counter += 1
}
timer?.fire()
Which would print for example:
0 2019-08-19 20:19:36 +0000 1 2019-08-19 20:19:37 +0000 2 2019-08-19 20:19:38 +0000 3 2019-08-19 20:19:39 +0000 4 2019-08-19 20:19:40 +0000 5 2019-08-19 20:19:41 +0000 6 2019-08-19 20:19:42 +0000 7 2019-08-19 20:19:43 +0000 8 2019-08-19 20:19:44 +0000 9 2019-08-19 20:19:45 +0000 10 2019-08-19 20:19:46 +0000
