macos - MacOSX - File extension associate with application - Programmatically

Question

I'm trying to get my program to automatically associate certain file extensions to be opened by it but I'm not sure how to do that in MacOSX. I'm not asking how to associate a program with a file extension in the GUI, I want to be able to program it into my program.

Answer 1

To register a new file extension with an application use the following defaults command.
Replace PUT_FILE_EXTENSION_HERE_WITHOUT_PERIOD with the file extension i.e. txt.
Replace org.category.program with the com/org name of your program i.e. com.apple.itunes.

$ defaults write com.apple.LaunchServices LSHandlers -array-add 
"<dict><key>LSHandlerContentTag</key>
<string>PUT_FILE_EXTENSION_HERE_WITHOUT_PERIOD</string><key>LSHandlerContentTagClass</key>
<string>public.filename-extension</string><key>LSHandlerRoleAll</key>
<string>org.category.program</string></dict>"

Once you have added the file extension to the launch services, you must restart the launch services deamon so it will re-read the configuration file.

You can either run the command below to restart launch services, or simply restart your computer. Loging in/loging out also might do it but I haven't tried.

$ /System/Library/Frameworks/CoreServices.framework/Versions/A/Framework/LaunchServices.framework/Versions/A/Support/lsregister -kill -domain local -domain system -domain user