iphone - UIImageWriteToSavedPhotosAlbum save as PNG with transparency?

Question

I'm using UIImageWriteToSavedPhotosAlbum to save a UIImage to the user's photo album. The problem is that the image doesn't have transparency and is a JPG. I've got the pixel data set correctly to have transparency, but there doesn't seem to be a way to save in a transparency-supported format. Ideas?

EDIT: There is no way to accomplish this, however there are other ways to deliver PNG images to the user. One of which is to save the image in the Documents directory (as detailed below). Once you've done that, you can email it, save it in a database, etc. You just can't get it into the photo album (for now) unless it is a lossy non-transparent JPG.

Answer 1

As pointed out on this SO question there is a simple way to save pngs in your Photo Albums:

UIImage* image = ...;                                     // produce your image
NSData* imageData =  UIImagePNGRepresentation(image);     // get png representation
UIImage* pngImage = [UIImage imageWithData:imageData];    // rewrap
UIImageWriteToSavedPhotosAlbum(pngImage, nil, nil, nil);  // save to photo album