PauseResumeAnimation.swift

//2 functions to pause and resume animation, I take from here and convert to Swift.

func pauseLayer(layer: CALayer) {
    let pausedTime: CFTimeInterval = layer.convertTime(CACurrentMediaTime(), fromLayer: nil)
    layer.speed = 0.0
    layer.timeOffset = pausedTime
}

func resumeLayer(layer: CALayer) {
    let pausedTime: CFTimeInterval = layer.timeOffset
    layer.speed = 1.0
    layer.timeOffset = 0.0
    layer.beginTime = 0.0
    let timeSincePause: CFTimeInterval = layer.convertTime(CACurrentMediaTime(), fromLayer: nil) - pausedTime
    layer.beginTime = timeSincePause
}
//I have a button to pause or resume the animation which is initialed in viewDidLoad:

var pause = false
override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)
    UIView.animateWithDuration(10.5, delay:0.0, options: [], animations:{

        self.image.transform = CGAffineTransformMakeTranslation(0.0, 200)
        }, completion: nil)
}

@IBAction func changeState() {
    let layer = image.layer
    pause = !pause
    if pause {
        pauseLayer(layer)
    } else {
        resumeLayer(layer)
    }
}

//sourec: http://stackoverflow.com/questions/33994520/how-to-pause-and-resume-uiview-animatewithduration