Init accessors are a new feature in Swift 5.9, and they sit right alongside get and set accessors, and even the underscored _read and _modify accessors that have not been “officially” added to the language yet.

Init accessors allow you to write initializers that set computed properties in the type even before all of the stored properties are set. This was a necessity in order to make macros work as seamlessly as possible.

This is an excerpt from our series of episodes on the Observation framework in Swift.