if you want to use external or custom fonts in a swift ios app, just:
1. copy the font files into the project
2. in your info.plist file, add an entry called "Fonts provided by application" (xcode will autocomplete you)
3. now you have an array, in which you add the names of the fonts - each in its own string entry
and that's how you add custom fonts to your ios app - good luck!