Browsed Managing model data in your app.

Read Macro Observable().

Read The Swift Programming Language (5.10) Macros.

Whay Macro is called so? WiKi: Macro (computer science):

In computer programming, a macro (short for “macro instruction”; from Greek μακρο- ‘long, large’[1]) is a rule or pattern that specifies how a certain input should be mapped to a replacement output. Applying a macro to an input is known as macro expansion.

Read @Environment documentation.