Merge two UIImages

Question

I have imageA (taken from the users iPhone camera) and imageB, an image with a silly boarder (for eg) with plenty of transparent alpha space.

What I would like to to do

Answer 1

Note that for retina support you should use: UIGraphicsBeginImageContextWithOptions(size, YES, 0); // 0 means let iOS deal with scale for you

Answer 2

That code looks correct (though I would recommend converting it to use a created CGBitmapContext for thread-safety), but is imageB supposed to be a JPEG? JPEGs don't support transparency, so, in order for the blending to work, it should really be a PNG.