自定义 UIActivityIndicatorView

 //view 沿中心点旋转  -1逆向旋转 1正向旋转

        int direction = -1;

        CABasicAnimation* rotationAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];

        rotationAnimation.toValue = [NSNumber numberWithFloat:(2 * M_PI) * direction];

        rotationAnimation.duration = 1.0f;

        rotationAnimation.repeatCount = HUGE_VALF;

        rotationAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];

        [self.layer addAnimation:rotationAnimation forKey:@"rotateAnimation"];