IOS让图片循环转动

让图片360度旋转，M_PI 是 π 的宏定义，3.1415926

 UIImageView *iv = [[UIImageView alloc] initWithFrame:CGRectMake(-40, 350, 400, 400)];
[iv setImage:[UIImage imageNamed:@"7"]];
//CALayer *rotate_layer = iv.layer;
[self.view addSubview:iv];
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform"];
animation.delegate = self;
animation.toValue = [NSValue valueWithCATransform3D:CATransform3DMakeRotation(M_PI , 0, 0, 1.0)];
animation.duration = 30;
animation.cumulative = YES;
animation.repeatCount = INT_MAX;

[iv.layer addAnimation:animation forKey:@"animation"];