title: Custom MPVolumeView Thumb Image not vertically centered since iOS 5.1
body: <p>I'm building an application that needs an MPVolumeView to control the volume. It worked perfectly before iOS 5.1 but since the 5.1 update the thumb image is no longer vertically centered. I tried a few things like changing imagine dimensions, resizing my views (and slider) but nothing seems to work, the thumb is just not vertically centered anymore. The only way i get a centered thumb is if i use the default iOS one.</p>
  
  <p>I tried adding a UISlider to another view with the exact min, max and thumb image and that one is centered fine.</p>
  
  <p>Here is the code for the MPVolumeView:</p>
  
  <pre><code>MPVolumeView *volumeView;
  volumeView = [[[MPVolumeView alloc] initWithFrame:volumeViewHolder.bounds] autorelease];
  [volumeViewHolder addSubview:volumeView];
  
  UIView  *volumeViewSlider;
  for (UIView *view in [volumeView subviews])
  {
      if ([[[view class] description] isEqualToString:@"MPVolumeSlider"])
      {
          volumeViewSlider = view;
      }
  }
  
  [(UISlider *)volumeViewSlider setThumbImage:sliderHandleIcon forState:UIControlStateNormal];
      [(UISlider *)volumeViewSlider setMinimumTrackImage:leftTrackImage forState:UIControlStateNormal];
      [(UISlider *)volumeViewSlider setMaximumTrackImage:rightTrackImage forState:UIControlStateNormal];
  </code></pre>
  
  <p>volumeViewHolder is just a UIView thats 153x33. I put the thumb in green in the screenshot.
  <img src="https://i.stack.imgur.com/5kFtg.png" alt="enter image description here"></p>