Create Custom UTI - Swift/ObjC

Does anyone know how to create a custom UTI programmatically in preferable Swift, but I might be able to deal with ObjC here.

You can manually create them in XCode and there become entries in the applications pList… but I want to create them in a fashion similar to an Xojo Filetype

Curious what Xojo code you’re trying to emulate ?

Isn’t this

Dim jpegType As New FileType
jpegType.Name = "image/jpeg"
jpegType.MacType = "JPEG"
jpegType.MacCreator = "prvw"
jpegType.Extensions = "jpg;jpeg"

a programmatic version of

I do not know, but your screen shot appears as hot as sun (totally white on my dark screen: inverted colors).

I am starting to understand how good dark mode (El Capitan only have inverted colors) can be for some disabled people.