The full extent of what's new in Swift Playgrounds 3.0 isn't clear as of yet, but Apple's release notes for the beta update provide a bit of detail. The new version of the app allows Playground Books to contain directories of Swift code and resources that can be imported for use by any page in the book.
Modules in a book's Modules directory can also be imported to any page in the book. Apple's release notes for the update are below:
New in Swift Playgrounds 3.0 Beta:TestFlight users who previously signed up to beta test Swift Playgrounds have access to the beta, but it does not appear that Apple is allowing new testers to sign up at this time.
Playground Books can now contain directories of Swift code and resources that can be imported for use by any page in that book.
The ./Contents/UserModules/UserCode.playgroundmodule/Sources/UserSource.swift file is editable by users using the new source editor tab.
In addition, the modules in a book's Modules directory (.playgroundbook/Contents/Modules) can be imported by any page in the book, but can't be viewed or edited in the app.
Note: Swift Playgrounds 3.0 beta uses Swift 5 (swiftlang-1001.0.63.8). Code written using other versions of Swift may not work in UserModuleExample.playgroundbook.
Known Issues in Swift Playgrounds 3.0 Beta:
- A playground may get stuck executing when live issues are present. (47896251)
Workaround: Resolve the live issue, return to the document browser and open the playground again.
- A playground may get stuck after recording a movie. (42903135)
Workaround: Force close Swift Playgrounds from the App Switcher, then relaunch the app and open the playground again.
This is the first beta of Swift Playgrounds 3.0 that Apple has released. The current version of the app available to the public is version 2.2, released back in November.