Allows any kind of UIView to start spinning in a 360 rotation

UIView+Spinning.swift

import UIKit

extension UIView {
    func startSpinning() {
        let spinAnimation = CABasicAnimation()
        spinAnimation.fromValue = 0
        spinAnimation.toValue = M_PI * 2
        spinAnimation.duration = 2.5
        spinAnimation.repeatCount = Float.infinity
        spinAnimation.removedOnCompletion = false
        layer.addAnimation(spinAnimation, forKey: "transform.rotation.z")
    }

    func stopSpinning() {
        layer.removeAllAnimations()
    }
}