UIView Swift Tilting Animation

问题:

I have an UIImageView and I would like it so that when I call a function, the image goes from flat(the normal state), to a tilting to the right rotation(say maybe a 20 degree rotation), then back to it's flat(normal) state.

This is what I currently have, but I can't get the desired outcome.

extension UIView {

    func rotate(duration: CFTimeInterval = 2) {
        let rotateAnimation = CABasicAnimation(keyPath: "transform.rotation")
        rotateAnimation.fromValue = 0.0
        rotateAnimation.toValue = CGFloat(20)
        rotateAnimation.isRemovedOnCompletion = true
        rotateAnimation.duration = duration
        rotateAnimation.repeatCount=Float.infinity
        self.layer.add(rotateAnimation, forKey: nil)
    }

}

UIImageView.rotate()

回答1:

I tried Creating the above Animation and my tried code Is here

Required Declarations

///View Outlet - Image or UIView
@IBOutlet weak var baseView: UIImageView!

/// Timer - To make Animation in repititive State
var newNAimationTimer : Timer?    

/// Plus Degree
let degrees : CGFloat = 20.0
/// Minus Degree
let minusDegree : CGFloat = -20.0

Timer Functions

//MARK: Start Timer
    func startTimer()
    {
        /// Start timer if Timer is Not Initialised Before
        if newNAimationTimer == nil {
            /// Assign Timer
            newNAimationTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(animationVC.animateView), userInfo: nil, repeats: true)
        }
    }

    //MARK: Stop Timer
    func stopTimer()
    {
        ///Check Do timer is Initialised
        if newNAimationTimer != nil {
            /// Yes Stop
            newNAimationTimer?.invalidate()
        }
    }

Timer Handler

/// Animate View With Animations
    @objc func animateView()
    {
        let plusRadian : CGFloat = degrees * CGFloat((Double.pi/180))
        let minusRadian : CGFloat = minusDegree * CGFloat((Double.pi/180))

        /// First Animation To make View Goes clockwise
        UIView.animate(withDuration: 0.5, animations: {
             self.baseView.transform = CGAffineTransform(rotationAngle: plusRadian)
        }) { (success) in
            /// Second Animation to make view go antiClockWise
            UIView.animate(withDuration: 0.5, animations: {
                self.baseView.transform = CGAffineTransform(rotationAngle: minusRadian)
            })
        }
    }

Button Action

@IBAction func animationButton(_ sender: Any) {
        /// Start the Animation
        startTimer()
    }

ScreenShots

First :

Second:

Running Output