title: Change colour of dark grey highlight when holding down custom UIButton?
body: <p>I have a custom <code>UIButton</code> which is a cloud, transparent black and white .png file, with no down state, just one image. When tapping and holding the finger over it, it turns dark grey. I'm trying to change that dark grey to something a little less oppressive. The button is out in the open in a view, not in a tab bar, tool bar, or navigation controller.</p>
  
  <p>I've already tried setting <code>tintColor</code> (which the documentation helpfully informs me is only suitable for 'some' types of buttons, which no indication as to which).</p>
  
  <p>I've also tried changing everything I can find in Interface Builder relating to highlight colours, default states, etc. Nothing has made a difference at all.</p>
  
  <p>I've even tried setting the button's own image for its <code>UIControlStateHighlighted</code> state, but even this causes the dark grey overlay to appear when I hold my finger over it.</p>
  
  <p>How can I change that colour? I've looked at numerous other issues here on SO and have been unable to find a solution that works for me. Any help would be greatly appreciated!</p>
  
  <p><strong>EDIT:</strong> I Solved the problem using a category of <code>UIImage</code> which adds a method that uses <code>CoreGraphics</code> to apply a tint to a provided <code>UIImage</code>. I then set THAT image as the highlight, and all is well. Seems a lot of hoop-la to change a colour Apple should've let us change, but c'est la vie.</p>