Detecting that iOS image data is HEIF or HEIC

Question

My server doesn't support the HEIF format. So I need to transform it to JPEG before uploading from my app.

I do this:

UIImage *image = [UIImage imageWithData:imageData];                                 
NSData *data=UIImageJPEGRepresentation(image, 1.0);

But how can I know that the data is HEIF (or HEIC) ? I can look at a file:

([filePath hasSuffix:@".HEIC"] || [filePath hasSuffix:@".heic"])

But I don't think it's a good answer. Is there any other solution?

Answer 1

A bit late to the party, but other than checking the extension (after the last dot), you can also check for the "magic number" aka file signature. Byte 5 to 8 should give you the constant "ftyp". The following 4 bytes would be the major brand, which I believe is one of "mif1", "heic" and "heix". For example, the first 12 bytes of a .heic image would be:

00 00 00 18 66 74 79 70 6d 69 66 31

which, after removing 0s and trim the result, literally decoded to ftypmif1.