How to repeat every X seconds in Swift?

Question

I am trying to build a simple single view app which runs an infinite slide show of a selection of images with a time delay between each image change.

The code I wrote for this is below. I tried to put this into viewDidLoad and viewDidAppear but the screen remained blank which I guess is because the function never finishes due to the infinite loop.

I learnt a bit of Python before iOS and with tkinter, your code would go into the mainloop. But I am not quite sure how to do the equivalent in Swift

Could someone please explain why I am having this problem and how to do this in Swift. Thanks.

var arrayimages: [UIImage] = [UIImage(named: "charizard")!,UIImage(named:"Flying_Iron_Man")!]

var x: Int = 0
var images: UIImage
let arraycount = arrayimages.count

repeat{
    images = arrayimages[(x % arraycount)]
    sleep(1)
    slideshow.image = images
    x++
} while true

NB: slideshow is an image view outlet.

Answer 1

You're looking for NSTimer

let timer = NSTimer.scheduledTimerWithTimeInterval(
    1.0, target: self, selector: Selector("doYourTask"),
    userInfo: nil, repeats: true)

The first argument is how frequently you want the timer to fire, the second is what object is going to have the selector that gets called, the third is the selector name, the fourth is any extra information you want to pass as a parameter on the timer object, and the fifth is whether this should repeat.

If you want to stop the code at any future point:

timer.invalidate()