False positive: NSPrincipalClass key is ignored

[Cykelero]

Summary

Setting a custom principal class (as declared in the Info.plist file under the NSPrincipalClass key) is not recognized by Periphery. This means it can report the class as being unused, even though the class is instantiated by the system on app launch.

Reproducing

• Create a new Storyboard/Swift app
• Create a UIApplication or NSApplication subclass
• In the project's build settings, set “Principal Class” to your class (in the ModuleName.ClassName form)
• Run periphery: it reports the class as unused