Your comments

Hi Alexander,


> The whole system only works if the file extension is known to the system. An extension like ".abc" is not known to the system and cannot work


File extensions .c and .cpp belong to the "public.source-code" group you've mentioned.

I have both .c and .cpp files on my Google Drive - but they are *grayed out*, so I cannot open them in Textastic.

Maybe Textastic really uses "public.text" only, but not "public.source-code".


> I also uploaded a .txt and an .html file on my desktop computer using https://d> rive.google.com/drive/my-drive and could successfully open it using the Open… command in Textastic.


Please try to upload a .c file.