22.3 Observable Objects
State properties provide a way to locally store the state of a view, are available only to the local view and, as such, cannot be accessed by other views unless they are subviews and state binding is implemented. State properties are also transient in that when the parent view goes away the state is also lost. Observable objects, on the other hand are used to represent persistent data that is both external and accessible to multiple views.
An Observable object takes the form of a class or structure that conforms to the ObservableObject protocol. Though the implementation of an observable object will be application specific depending on the nature and source of the data, it will typically be responsible for gathering and managing one or more data values that are known to change over time. Observable objects can also be used to handle events such as timers and notifications.
The observable object publishes the data values for which it is responsible as published...
