ios UIButton一直旋转动画

-(void)viewDidAppear:(BOOL)animated{
​ UIButton * buyBtn = [[UIButton alloc]initWithFrame:CGRectMake(10, 0, 50, 50)];
[buyBtn setImage:[UIImage imageNamed:@"AppIcon40x40"] forState:UIControlStateNormal];
[segmentView2 addSubview:buyBtn];
buyBtn=[self rotate360DegreeWithImageView:buyBtn];
}

• (UIButton *)rotate360DegreeWithImageView:(UIButton *)imageView{

  CABasicAnimation *animation = [ CABasicAnimation animationWithKeyPath: @"transform" ];

  animation.fromValue = [NSValue valueWithCATransform3D:CATransform3DIdentity];

  //围绕Z轴旋转，垂直与屏幕

  animation.toValue = [ NSValue valueWithCATransform3D:CATransform3DMakeRotation(M_PI/2.0, 0.0, 0.0, 1.0) ];

  animation.duration = 3;

  //旋转效果累计，先转180度，接着再旋转180度，从而实现360旋转

  animation.cumulative = YES;

  animation.repeatCount = MAXFLOAT;

  /*下面可以不需要
  CGRect imageRrect = CGRectMake(0, 0,imageView.imageView.frame.size.width, imageView.imageView.frame.size.height);
  UIGraphicsBeginImageContext(imageRrect.size);
  //在图片边缘添加一个像素的透明区域，去图片锯齿
  [imageView.currentImage drawInRect:CGRectMake(1,1,imageView.imageView.frame.size.width-2,imageView.imageView.frame.size.height-2)];
  [imageView setImage: UIGraphicsGetImageFromCurrentImageContext() forState:UIControlStateNormal];
  UIGraphicsEndImageContext();
  */
  [imageView.layer addAnimation:animation forKey:nil];

  return imageView;
  }