
What you need to do is add your file type definition to the application that opens it by default, or create your own "dummy" application for the file type.Īs an example, my system does not yet know about. Preview provides PDF icons by default, and PNG icons, but if you change all PNG files to open using Pixelmator instead, these files get a Pixelmator-style icon afterwards. The file icon is always provided by the application handling opening a file by default. Icons for file types are handled by Launch Services (the service determining, among other things, which application handles a file type).
