A simple project demonstrating how to add new actions to Apple's Shortcuts app.
Step-by-step tutorials accompany this project:
Part 1: Creating a project and adding the first action
Part 2: Exploring parameters: arrays, enums, calculated lists and files
Part 3: In-app intent handling, custom output types, visual list API and using the SwiftUI app protocol
Part 3 has a new iOS 14 project, which you can see here.