Create a UIProgressView to go from 0.0 (empty) to 1.0 (full) in 3 seconds

Question

Basically I want to create a UIProgressView to go from 0.0 (empty) to 1.0 (full) in 3 seconds. Could anyone point me in the right direction for using NSTimer in swift with UIProgressView?

Answer 1

I created my own solution after searching for one and coming across this question.

extension UIProgressView {

    func setAnimatedProgress(progress: Float,
        duration: NSTimeInterval = 1,
        delay: NSTimeInterval = 0,
        completion: () -> ()
    ) {
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0)) {
            sleep(UInt32(delay))
            dispatch_async(dispatch_get_main_queue()) {
                self.layer.speed = Float(pow(duration, -1))
                self.setProgress(progress, animated: true)
            }
            sleep(UInt32(duration))
            dispatch_async(dispatch_get_main_queue()) {
                self.layer.speed = 1
                completion()
            }
        }
    }
}

Answer 2

Declare the properties:

var time = 0.0
var timer: NSTimer

Initialize the timer:

timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector:Selector("setProgress"), userInfo: nil, repeats: true)

Implement the setProgress function:

func setProgress() {
    time += 0.1
    dispatch_async(dispatch_get_main_queue(), {
        progressView.progress = time / 3 
    })
    if time >= 3 {
        timer.invalidate()
    }
}

(I'm not 100% sure if the dispatch block is necessary, to make sure the UI is updated in the main thread. Feel free to remove this if it isn't necessary.)

Answer 3

If anyone's interested here is a Swift 5 working version :

extension UIProgressView {
    @available(iOS 10.0, *)
    func setAnimatedProgress(progress: Float = 1, duration: Float = 1, completion: (() -> ())? = nil) {
        Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { (timer) in
            DispatchQueue.main.async {
                let current = self.progress
                self.setProgress(current+(1/duration), animated: true)
            }
            if self.progress >= progress {
                timer.invalidate()
                if completion != nil {
                    completion!()
                }
            }
        }
    }
}

Usage :

// Will fill the progress bar in 70 seconds
self.progressBar.setAnimatedProgress(duration: 70) {
    print("Done!")
}