observation-documentation

Observation Documentation Index

Fetch from this index before implementing any Observation feature — do not guess at behavior. One URL per topic — read the most specific one first.

Discovery

• https://developer.apple.com/documentation/observation — Main Observation framework page; overview, topic sections, and sample code.

Observable Conformance

• https://developer.apple.com/documentation/observation/observable() — @Observable macro: declares and implements conformance to the Observable protocol at compile time.
• https://developer.apple.com/documentation/observation/observable — Observable protocol: type that emits notifications to observers when underlying data changes.

Change Tracking

• https://developer.apple.com/documentation/observation/withobservationtracking(_:onchange:) — withObservationTracking function: tracks access to properties within a closure and calls onChange when a tracked property changes.
• https://developer.apple.com/documentation/observation/observationregistrar — ObservationRegistrar struct: provides storage for tracking and access to data changes.
• https://developer.apple.com/documentation/observation/observationregistrar/init() — init(): creates an instance of the observation registrar.
• https://developer.apple.com/documentation/observation/observationregistrar/willset(_:keypath:) — willSet(_:keyPath:): property observation called before setting the value of the subject.
• https://developer.apple.com/documentation/observation/observationregistrar/didset(_:keypath:) — didSet(_:keyPath:): property observation called after setting the value of the subject.
• https://developer.apple.com/documentation/observation/observationregistrar/access(_:keypath:) — access(_:keyPath:): registers access to a specific property for observation.
• https://developer.apple.com/documentation/observation/observationregistrar/withmutation(of:keypath:_:) — withMutation(of:keyPath:_:): identifies mutations to the transactions registered for observers.

Async Observation

• https://developer.apple.com/documentation/observation/observations — Observations struct: async sequence generated from a closure that tracks transactional changes of @Observable types.
• https://developer.apple.com/documentation/observation/observations/init(_:) — init(_:): constructs an async sequence by tracking changes of @Observable types.
• https://developer.apple.com/documentation/observation/observations/untilfinished(_:) — untilFinished(_:): constructs an async sequence for a given closure, tracking changes of @Observable types.
• https://developer.apple.com/documentation/observation/observations/iterator — Observations.Iterator: iterator for the Observations async sequence.
• https://developer.apple.com/documentation/observation/observations/iteration — Observations.Iteration: enumeration for iteration state.

Selective Observation

• https://developer.apple.com/documentation/observation/observationignored() — @ObservationIgnored macro: disables observation tracking of a property.
• https://developer.apple.com/documentation/observation/observationtracked() — @ObservationTracked macro: synthesizes a property for accessors (used internally by @Observable).

SwiftUI Integration

• https://developer.apple.com/documentation/swiftui/managing-model-data-in-your-app — Managing model data in your app: creating connections between your app's data model and views.
• https://developer.apple.com/documentation/swiftui/migrating-from-the-observable-object-protocol-to-the-observable-macro — Migrating from ObservableObject to Observable: updating existing apps to leverage Observation.