Rotate a view for 360 degrees indefinitely in Swift?

Question

I want to rotate an image view for 360 degrees indefinitely.

UIView.animate(withDuration: 2, delay: 0, options: [.repeat], animations: {
    self.view.transf         


        

Answer 1

I think what you really want here is to use a CADisplayLink. Reason being that this would be indefinitely smooth versus using completion blocks which may cause slight hiccups and are not as easily cancelable. See the following solution:

var displayLink : CADisplayLink?
var targetView = UIView()

func beginRotation () {

    // Setup display link
    self.displayLink = CADisplayLink(target: self, selector: #selector(onFrameInterval(displayLink:)))
    self.displayLink?.preferredFramesPerSecond = 60
    self.displayLink?.add(to: .current, forMode: RunLoop.Mode.default)
}

func stopRotation () {

    // Invalidate display link
    self.displayLink?.invalidate()
    self.displayLink = nil
}

// Called everytime the display is refreshed
@objc func onFrameInterval (displayLink: CADisplayLink) {

    // Get frames per second
    let framesPerSecond = Double(displayLink.preferredFramesPerSecond)

    // Based on fps, calculate how much target view should spin each interval
    let rotationsPerSecond = Double(3)
    let anglePerSecond = rotationsPerSecond * (2 * Double.pi)
    let anglePerInterval = CGFloat(anglePerSecond / framesPerSecond)

    // Rotate target view to match the current angle of the interval
    self.targetView.layer.transform = CATransform3DRotate(self.targetView.layer.transform, anglePerInterval, 0, 0, 1)

}