title: Rotate UIImageView clockwise
body: <p>This should be simple, but I'm having trouble rotating a <code>UIImageView</code> a full 360 degrees, repeated forever.</p>
  
  <pre><code>[UIView animateWithDuration:0.5 delay:0 options:UIViewAnimationOptionAllowUserInteraction | UIViewAnimationOptionRepeat | UIViewAnimationOptionCurveLinear | UIViewAnimationOptionBeginFromCurrentState animations:^{
      self.reloadButton.imageView.transform = CGAffineTransformRotate(self.reloadButton.imageView.transform, -M_PI);
  } completion:^(BOOL finished) {
  
  }];
  </code></pre>
  
  <p>According to the docs, the signedness of the angle I pass to <code>CGAffineTransformRotate</code> determines the direction of the rotation, but the above code rotates counterclockwise. Same with <code>M_PI</code>.</p>
  
  <blockquote>
    <p>The angle, in radians, by which this matrix rotates the coordinate
    system axes. In iOS, a positive value specifies counterclockwise
    rotation and a negative value specifies clockwise rotation. In Mac OS
    X, a positive value specifies clockwise rotation and a negative value
    specifies counterclockwise rotation.</p>
  </blockquote>