How to preserve XMP metadata in Objective C?
metadata, xmp
Solution
Yes.
- Use Adobe XMP SDK.
Read the metadata from the image when you open it using:
`SXMPFiles myFile;`
`ok = myFile.OpenFile(filename, kXMP_UnknownFile, opts);`
`myFile.GetXMP(_meta); // _meta is a data member of the class that represents your photo (probably a subclass of NSDocument).`
When saving the image, write the image content, then write `_meta` to the output file using SXMPFiles.PutXMP(...), and then set specific metadata entries that you like.
See Adobe XMP programming guide for more details about reading and writing XMP metadata.
Problem
I need my photo-editor app to preserve unknown metadata entries that were existing in the original photo that was opened by my app (for example, non-standard XMP meta-data) I tried to use the Apple's built-in meta-data read/write meta-data, with no success. Is there a way to just copy all existing meta-data to a buffer, write it as-is and then change only specific entries?