Playgrounds for apollo-ios

The playgrounds in this project cover the following features of apollo-ios and GraphQL:

• Queries, the most basic GraphQL operation
• Mutations, used to change a piece of information on the server
• Subscriptions, use a websocket connection to subscribe to updates to a particular query
• SQLite caching, setting up an Apollo client with a SQLite cache
• Custom scalars, define your own scalar types based on existing GraphQL scalar types

This project and the playgrounds work best with Xcode 13.