System

Foundation · IOS API REFERENCE

NotificationCenter.MessageIdentifier

protocol · iOS 26.0+ · SDK 27.1

protocol MessageIdentifier

An optional identifier to associate a given message with a given type. Implement a `MessageIdentifier` to provide a typed, ergonomic experience at the call point, as described in [SE-0299](https://github.com/swiftlang/swift-evolution/blob/main/proposals/0299-extend-generic-static-member-lookup.md). For example, given `ExampleMessage` with a `Subject` called `ExampleSubject`: ```swift extension NotificationCenter.MessageIdentifier where Self == NotificationCenter.BaseMessageIdentifier<ExampleMessage> { static var eventDidOccur: Self { .init() } } ``` This simplifies the call point for clients, as seen here: ```swift let token = center.addObserver(of: exampleSubject, for: .eventDidOccur) { ... } ```

Members (0)

This type has no directly callable members in this snapshot. See the framework’s skipped declarations for unsupported APIs.

Skipped declarations

31 declarations were excluded from these bindings. Each reason comes from the generator or the iOS SDK compiler.

NotificationCenter.MessageIdentifier.cookiesChanged

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.willUndoChange

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.didUndoChange

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.willRedoChange

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.didRedoChange

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.checkpoint

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.didOpenUndoGroup

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.didCloseUndoGroup

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.willCloseUndoGroup

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.didFinishGathering

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.didStartGathering

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.calendarDayChanged

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.systemClockDidChange

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.systemTimeZoneDidChange

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.powerStateDidChange

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.thermalStateDidChange

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.connectionAccepted

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.dataAvailable

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.readToEndOfFileCompletion

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.readCompletion

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.didLoad

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.didChange

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.sizeLimitExceeded

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.didBecomeInvalid

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.currentLocaleDidChange

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.ubiquityIdentityDidChange

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.lowDiskSpace

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.didBecomeActive

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.didEnterBackground

Static protocol requirements cannot be called through an instance.

NotificationCenter.MessageIdentifier.willEnterForeground

Static protocol requirements cannot be called through an instance.

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