title: iPhone, how does one overlay one image onto another to create a new image to save? (watermark)
body: <p>Basically I want to take an image that the user chooses from their photo library and then apply a watermark, a triangle in the lower right that has the app name on it. I have the second image already made with a transparent layer in photoshop.</p>
  
  <p>I tried a function, which I can't remember the exact name, but it involved CGIImages and masks. This combines the two images, but as a mask, which made the image darker where the transparent layer was and the images were not merged per se, just masked.</p>
  
  <p>How would I get the watermark image to merge with another image, to make a UIImage, without displaying the images on the screen?</p>
  
  <p>Thank you.</p>