Swift 图片翻转

第一种：

  UIView.animate(withDuration: 0.3) {
       self.arrowImageView.layer.transform = CATransform3DRotate(self.arrowImageView.layer.transform, .pi, 1.0, 0.0, 0.0)
  }

第二种：

arrowImageView.transform = .identity  //默认
arrowImageView.transform =  CGAffineTransform.init(rotationAngle: .pi) //翻转180°

if isShowList {
      arrowImageView.transform =  CGAffineTransform.init(rotationAngle: .pi)
 } else {
      arrowImageView.transform = .identity
 }