I have lot of experience with other programming languages, but not so much in swift 3. I want to do polling loop. This is what i have written:
DispatchQueue.global(qos: .userInitiated).async {
[unowned self] in
while self.isRunning {
WebService.getPeople(completion: nil)
sleep(100)
}
}
This works fine for me, every 100 seconds, i do polling, and then make this thread sleep. What I am wondering, is this correct way to do this in swift 3?
You have 2 options:
NSTimer
DispatchSourceTimer
Using NSTimer
is pretty easy, but it needs an active run loop, so if you need to poll on a background thread things could be a little bit tricky, because you will need to create a thread and keep alive a run loop on it (probably the timer itself will keep the run loop alive).DispatchSourceTimer
on the other hand works using queues
. You can easily create a dispatch source timer from one of the system provided queues or create one.
var timer: DispatchSourceTimer?
let queue = DispatchQueue.global(qos: .background)
guard let timer = DispatchSource.makeTimerSource(queue: queue) else { return }
timer.scheduleRepeating(deadline: .now(), interval: .seconds(100), leeway: .seconds(1))
timer.setEventHandler(handler: {
// Your code
})
timer.resume()
The leeway
arguments is the amount of time that the system can defer the timer.
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