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

Updated for Swift 3: I made an extension to UIView and included the following function within:

func rotate(fromValue: CGFloat, toValue: CGFloat, duration: CFTimeInterval = 1.0, completionDelegate: Any? = nil) {

let rotateAnimation = CABasicAnimation(keyPath: >"transform.rotation")
rotateAnimation.fromValue = fromValue
rotateAnimation.toValue = toValue
rotateAnimation.duration = duration

if let delegate: Any = completionDelegate {
rotateAnimation.delegate = delegate as? CAAnimationDelegate
}
self.layer.add(rotateAnimation, forKey: nil)

}

You can then call the function via (on a UIView I made into a button for example) :

monitorButton.rotate(fromValue: 0.0, toValue: CGFloat(M_PI * 2), completionDelegate: self)

Hope this helps!

Answer 2

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)

}

Answer 3

Swift 3.0

let imgViewRing = UIImageView(image: UIImage(named: "apple"))
imgViewRing.frame = CGRect(x: 0, y: 0, width: UIImage(named: "apple")!.size.width, height: UIImage(named: "apple")!.size.height)
imgViewRing.center = CGPoint(x: self.view.frame.size.width/2.0, y: self.view.frame.size.height/2.0)
rotateAnimation(imageView: imgViewRing)
self.view.addSubview(imgViewRing)

This is the animation logic

func rotateAnimation(imageView:UIImageView,duration: CFTimeInterval = 2.0) {
        let rotateAnimation = CABasicAnimation(keyPath: "transform.rotation")
        rotateAnimation.fromValue = 0.0
        rotateAnimation.toValue = CGFloat(.pi * 2.0)
        rotateAnimation.duration = duration
        rotateAnimation.repeatCount = .greatestFiniteMagnitude

        imageView.layer.add(rotateAnimation, forKey: nil)
    }

You can check output in this link

Answer 4

Avoiding the completion closure with recursive calls!

Bit late to this party, but using UIView keyFrame animation & varying stages of rotation for each keyFrame, plus setting the animation curve works nicely. Here's an UIView class function -

class func rotate360(_ view: UIView, duration: TimeInterval, repeating: Bool = true) {

    let transform1 = CGAffineTransform(rotationAngle: .pi * 0.75)
    let transform2 = CGAffineTransform(rotationAngle: .pi * 1.5)

    let animationOptions: UInt
    if repeating {
        animationOptions = UIView.AnimationOptions.curveLinear.rawValue | UIView.AnimationOptions.repeat.rawValue
    } else {
        animationOptions = UIView.AnimationOptions.curveLinear.rawValue
    }

    let keyFrameAnimationOptions = UIView.KeyframeAnimationOptions(rawValue: animationOptions)

    UIView.animateKeyframes(withDuration: duration, delay: 0, options: [keyFrameAnimationOptions, .calculationModeLinear], animations: {
        UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 0.375) {
            view.transform = transform1
        }
        UIView.addKeyframe(withRelativeStartTime: 0.375, relativeDuration: 0.375) {
            view.transform = transform2
        }
        UIView.addKeyframe(withRelativeStartTime: 0.75, relativeDuration: 0.25) {
            view.transform = .identity
        }
    }, completion: nil)
}

Looks pretty gnarly, with the weird rotation angles, but as the op & others have found, you can't just tell it to rotate 360