How to draw an CGImage with some alpha transparency?
<p>Want to draw an UIImageView which has an CGImage, and the UIImageView has alpha 0.5f. But this CGContextDrawImage function doesnt take an transparency value. So how could I draw an image slightly transparent?</p>

<p>To be clear: The image itself is not transparent, but I want it to be "dimmed" a little bit. Just like you would do with an UIImageView and some alpha like 0.5f :-)</p>
