1. The document discusses Swift Package Manager (SwiftPM), a new package manager for Swift packages and modules introduced in Xcode 8 and Swift 3.
2. SwiftPM allows defining packages and dependencies through a Package.swift file and building and linking packages through the swift build and swift run commands.
3. The author provides an example of initializing a package with SwiftPM, adding a dependency, building and running the package to summarize how SwiftPM works at a high level.
21. $ swift build
➜ Potatotips swift build
Cloning git@github.com:apple/example-package-playingcard.git
HEAD is now at 6e772a6 Fixing a Linux-specific test failure.
Resolved version: 3.0.1
Compile Swift Module 'PlayingCard' (3 sources)
Compile Swift Module 'Potatotips' (1 sources)
Linking ./.build/debug/Potatotips