Swift Continuous Rotation Animation not so continuous

Try below extension for swift 4.

extension UIView {
    func rotate360Degrees(duration: CFTimeInterval = 3) {
        let rotateAnimation = CABasicAnimation(keyPath: "transform.rotation")
        rotateAnimation.fromValue = 0.0
        rotateAnimation.toValue = CGFloat(Double.pi * 2)
        rotateAnimation.isRemovedOnCompletion = false
        rotateAnimation.duration = duration
        rotateAnimation.repeatCount=Float.infinity
        self.layer.add(rotateAnimation, forKey: nil)
    }
}

For start rotation.

MyView.rotate360Degrees()

And for Stop.

MyView.layer.removeAllAnimations()

You can use UIButton, UILabel and many more.

I'm not sure what's wrong with your code, but I've implemented continuous rotation using this method,

@IBAction func rotateView(sender: UIButton) {
    UIView.animate(withDuration: 0.5, delay: 0, options: .curveLinear, animations: { () -> Void in
        self.spinningView.transform = self.spinningView.transform.rotated(by: .pi / 2)
    }) { (finished) -> Void in
        self.rotateView(sender: sender)
    }
}

If you want to continuous rotate Button or View and stop that rotation whenever you want then you can try this: For start rotation:

@IBOutlet weak var RotateBtn: UIButton!
var timeTimer: Timer?

viewDidLoad()
{
  self.rotateView()
  timeTimer = Timer.scheduledTimer(timeInterval: 0.5, target: self, selector: #selector(self.rotateView), userInfo: nil, repeats: true)
}

func rotateView()
{
    UIView.animate(withDuration: 0.5, delay: 0, options: .curveLinear, animations: { () -> Void in
        self.RotateBtn.transform = self.RotateBtn.transform.rotated(by: CGFloat(M_PI_4))
    })
}

If you want to stop rotation then use:

@IBAction func StopBtn_Pressed(_ sender: AnyObject)
{
   timeTimer?.invalidate()
   self.RecordBtn.layer.removeAllAnimations()
}