Rotate NSImageView (UIImageView) around its center

ImageRotation.swift

extension NSView { // UIView
    // Set source/destination angle.
    // Angle is set in radians (0..2π), hence 360* rotation = 2π/-2π
 
    func spinClockwise(timeToRotate: Double) {
        startRotation(angle: -1 * CGFloat.pi * 2.0, timeToRotate: timeToRotate)
    }
 
    func spinAntiClockwise(timeToRotate: Double) {
        startRotation(angle: CGFloat.pi * 2.0, timeToRotate: timeToRotate)
    }
 
    func startRotation(angle: CGFloat, timeToRotate: Double) {
        let rotateAnimation = CABasicAnimation(keyPath: "transform.rotation")
        rotateAnimation.fromValue = 0.0
        rotateAnimation.toValue = angle
        rotateAnimation.duration = timeToRotate
        rotateAnimation.speed = 4
        rotateAnimation.repeatCount = .infinity
 
        self.layer?.add(rotateAnimation, forKey: nil)
 
        Swift.print("Start rotating")
    }
 
    func stopAnimations() {
        self.layer?.removeAllAnimations()
        Swift.print("Stop rotating")
    }
}

// Usage:
imageView.wantsLayer = true
imageView.layer!.anchorPoint = CGPoint(x: 0.5, y: 0.5) // 0.5x0.5 means center

// Start spinning
imageView.spinClockwise(timeToRotate: 60)
 
// Stop spinning
imageView.stopAnimations()