swap_animation.swift

let circlePath2 = UIBezierPath(arcCenter: CGPoint(x: self.swapBtn.frame.midX, y:  self.swapBtn.frame.midY), radius: -self.frame.width/3, startAngle: CGFloat(M_PI * 2.0), endAngle: CGFloat(M_PI) , clockwise: false)
        let animation2 = CAKeyframeAnimation(keyPath: "position");
        animation2.duration = 0.7
        animation2.repeatCount = MAXFLOAT
        animation2.path = circlePath2.cgPath
        animation2.repeatCount = 0
        animation2.fillMode = kCAFillModeForwards
        animation2.isRemovedOnCompletion = false
        let circlePath = UIBezierPath(arcCenter: CGPoint(x: self.swapBtn.frame.midX, y:  self.swapBtn.frame.midY), radius: -self.frame.width/3, startAngle:  CGFloat(M_PI) , endAngle: CGFloat(M_PI * 2.0) , clockwise: true)
        let animation = CAKeyframeAnimation(keyPath: "position");
        animation.duration = 0.7
        animation.repeatCount = MAXFLOAT
        animation.path = circlePath.cgPath
        animation.repeatCount = 0
        animation.fillMode = kCAFillModeForwards
        animation.isRemovedOnCompletion = false
        to.layer.add(animation2, forKey: nil)
        from.layer.add(animation, forKey: nil)
        let buf = from
        from = to
        to = buf