If you want to build an iOS app with Swift, the built-in frameworks give you everything you need. Swift as a language, Cocoa Touch (includes Foundation as a kin

If you want to build an iOS app with Swift, the built-in frameworks give you everything you need. Swift as a language, Cocoa Touch (includes Foundation as a kind of standard library and UIKit or SwiftUI for the UI stuff), Xcode for the IDE and build system. There's one source of documentation, Apple, and there's years of third-party documentation all over the internet. You can bring in libraries of course, but even for a large iOS project it's unlikely (and probably unnecessary) to have more than a handful.