title: Transparent row of pixels between section header and first cell in a grouped UITableView
body: <p>As the title says, I have a problem with a row of transparent pixels that I can't get rid off.<br />
  I attached an image as it's worth 1000 words.</p>
  <p><a href="https://i.stack.imgur.com/AhU1T.png" rel="noreferrer"><img src="https://i.stack.imgur.com/AhU1T.png" alt="" /></a></p>
  
  <p>The problem is not present for the section footer (where I'm also using a custom view).
  I have checked and double checked that I return the correct size for the height of the section.</p>
  <p>Any ideas?</p>
  <p><strong>EDIT:</strong><br />
  I've added a test project so you can play around. The purple color represents the background color. The white rectangles are the header/footer and the light gray are some dummy cells. The issue is clearly visible in the project.</p>
  <p><a href="https://www.2shared.com/file/R0oCuu0e/TransparentRowBug.html" rel="noreferrer">TransparentRowBug XCode project</a></p>
  <p>You will also see that I use a lot of clear colors. Unfortunately changing the colors in order to hide the problem is not a viable solution for me.</p>
  <p>Feel free to give it a try (or more)!</p>
  <p>Thanks a lot!</p>
  <p><strong>EDIT2:</strong><br />
  After further investigation, I concluded that the line of pixels come from the tableview separator. In the test project I am setting the separatorColor to clearColor. If I change this to another color, I will get exactly that row of pixels in the new color. Even though I set the separator style to none, it seems to have no effect on grouped tables.</p>