---
title: NotificationCenter.MessageIdentifier
framework: foundation
role: symbol
role_heading: Protocol
path: foundation/notificationcenter/messageidentifier
---

# NotificationCenter.MessageIdentifier

An optional identifier to associate a given message with a given type.

## Declaration

```swift
protocol MessageIdentifier
```

## Overview

Overview Implement a MessageIdentifier to provide a typed, ergonomic experience at the call point, as described in SE-0299. For example, given ExampleMessage with a Subject called ExampleSubject: extension NotificationCenter.MessageIdentifier where Self == NotificationCenter.BaseMessageIdentifier<ExampleMessage> {     static var eventDidOccur: Self { .init() } } This simplifies the call point for clients, as seen here: let token = center.addObserver(of: exampleSubject, for: .eventDidOccur) { ... }

## Topics

### Declaring the message type

- [MessageType](foundation/notificationcenter/messageidentifier/messagetype.md)

### Identifying cookie storage messages

- [cookiesChanged](foundation/notificationcenter/messageidentifier/cookieschanged.md)

### Identifying undo manager messages

- [willUndoChange](foundation/notificationcenter/messageidentifier/willundochange.md)
- [didUndoChange](foundation/notificationcenter/messageidentifier/didundochange.md)
- [willRedoChange](foundation/notificationcenter/messageidentifier/willredochange.md)
- [didRedoChange](foundation/notificationcenter/messageidentifier/didredochange.md)
- [checkpoint](foundation/notificationcenter/messageidentifier/checkpoint.md)
- [didOpenUndoGroup](foundation/notificationcenter/messageidentifier/didopenundogroup.md)
- [willCloseUndoGroup](foundation/notificationcenter/messageidentifier/willcloseundogroup.md)
- [didCloseUndoGroup](foundation/notificationcenter/messageidentifier/didcloseundogroup.md)

### Identifying defaults messages

- [didChange](foundation/notificationcenter/messageidentifier/didchange-187tw.md)
- [sizeLimitExceeded](foundation/notificationcenter/messageidentifier/sizelimitexceeded.md)

### Identifying metadata query messages

- [didStartGathering](foundation/notificationcenter/messageidentifier/didstartgathering.md)
- [didFinishGathering](foundation/notificationcenter/messageidentifier/didfinishgathering.md)

### Identifying calendar, date, and time zone messages

- [calendarDayChanged](foundation/notificationcenter/messageidentifier/calendardaychanged.md)
- [systemClockDidChange](foundation/notificationcenter/messageidentifier/systemclockdidchange.md)
- [systemTimeZoneDidChange](foundation/notificationcenter/messageidentifier/systemtimezonedidchange.md)

### Identifying locale messages

- [currentLocaleDidChange](foundation/notificationcenter/messageidentifier/currentlocaledidchange.md)

### Identifying bundle messages

- [didLoad](foundation/notificationcenter/messageidentifier/didload.md)

### Identifying process info messages

- [powerStateDidChange](foundation/notificationcenter/messageidentifier/powerstatedidchange.md)
- [thermalStateDidChange](foundation/notificationcenter/messageidentifier/thermalstatedidchange.md)
- [didTerminate](foundation/notificationcenter/messageidentifier/didterminate.md)

### Identifying file handle messages

- [connectionAccepted](foundation/notificationcenter/messageidentifier/connectionaccepted.md)
- [dataAvailable](foundation/notificationcenter/messageidentifier/dataavailable.md)
- [readToEndOfFileCompletion](foundation/notificationcenter/messageidentifier/readtoendoffilecompletion.md)
- [readCompletion](foundation/notificationcenter/messageidentifier/readcompletion.md)

### Identifying port messages

- [didBecomeInvalid](foundation/notificationcenter/messageidentifier/didbecomeinvalid.md)

### Identifying file manager messages

- [ubiquityIdentityDidChange](foundation/notificationcenter/messageidentifier/ubiquityidentitydidchange.md)

### Identifying bundle resource request messages

- [lowDiskSpace](foundation/notificationcenter/messageidentifier/lowdiskspace.md)

### Identifying extension messages

- [didBecomeActive](foundation/notificationcenter/messageidentifier/didbecomeactive-79dvm.md)
- [willResignActive](foundation/notificationcenter/messageidentifier/willresignactive-9z4xc.md)
- [didEnterBackground](foundation/notificationcenter/messageidentifier/didenterbackground-5gdtk.md)
- [willEnterForeground](foundation/notificationcenter/messageidentifier/willenterforeground-p1og.md)

### Identifying UIKit accessibility messages

- [switchControlStatusDidChange](foundation/notificationcenter/messageidentifier/switchcontrolstatusdidchange.md)
- [elementFocused](foundation/notificationcenter/messageidentifier/elementfocused.md)
- [reduceTransparencyStatusDidChange](foundation/notificationcenter/messageidentifier/reducetransparencystatusdidchange.md)
- [announcementDidFinish](foundation/notificationcenter/messageidentifier/announcementdidfinish.md)
- [boldTextStatusDidChange](foundation/notificationcenter/messageidentifier/boldtextstatusdidchange.md)
- [closedCaptioningStatusDidChange](foundation/notificationcenter/messageidentifier/closedcaptioningstatusdidchange.md)
- [darkerSystemColorsStatusDidChange](foundation/notificationcenter/messageidentifier/darkersystemcolorsstatusdidchange.md)
- [grayscaleStatusDidChange](foundation/notificationcenter/messageidentifier/grayscalestatusdidchange.md)
- [invertColorsStatusDidChange](foundation/notificationcenter/messageidentifier/invertcolorsstatusdidchange.md)
- [assistiveTouchStatusDidChange](foundation/notificationcenter/messageidentifier/assistivetouchstatusdidchange.md)
- [guidedAccessStatusDidChange](foundation/notificationcenter/messageidentifier/guidedaccessstatusdidchange.md)
- [monoAudioStatusDidChange](foundation/notificationcenter/messageidentifier/monoaudiostatusdidchange.md)
- [speakScreenStatusDidChange](foundation/notificationcenter/messageidentifier/speakscreenstatusdidchange.md)
- [speakSelectionStatusDidChange](foundation/notificationcenter/messageidentifier/speakselectionstatusdidchange.md)
- [hearingDevicePairedEarDidChange](foundation/notificationcenter/messageidentifier/hearingdevicepairedeardidchange.md)
- [reduceMotionStatusDidChange](foundation/notificationcenter/messageidentifier/reducemotionstatusdidchange.md)
- [shakeToUndoDidChange](foundation/notificationcenter/messageidentifier/shaketoundodidchange.md)
- [voiceOverStatusDidChange](foundation/notificationcenter/messageidentifier/voiceoverstatusdidchange.md)
- [buttonShapesEnabledStatusDidChange](foundation/notificationcenter/messageidentifier/buttonshapesenabledstatusdidchange.md)

### Identifying UIKit app life cycle messages

- [didFinishLaunching](foundation/notificationcenter/messageidentifier/didfinishlaunching.md)
- [didBecomeActive](foundation/notificationcenter/messageidentifier/didbecomeactive-2hcfs.md)
- [didEnterBackground](foundation/notificationcenter/messageidentifier/didenterbackground-1u5sm.md)
- [willEnterForeground](foundation/notificationcenter/messageidentifier/willenterforeground-95zi8.md)
- [willResignActive](foundation/notificationcenter/messageidentifier/willresignactive-4rf2p.md)
- [didReceiveMemoryWarning](foundation/notificationcenter/messageidentifier/didreceivememorywarning.md)
- [significantTimeChange](foundation/notificationcenter/messageidentifier/significanttimechange.md)
- [backgroundRefreshStatusDidChange](foundation/notificationcenter/messageidentifier/backgroundrefreshstatusdidchange.md)
- [userDidTakeScreenshot](foundation/notificationcenter/messageidentifier/userdidtakescreenshot.md)

### Identifying UIKit content size messages

- [contentSizeCategoryDidChange](foundation/notificationcenter/messageidentifier/contentsizecategorydidchange.md)

### Identifying UIKIt device messages

- [batteryLevelDidChange](foundation/notificationcenter/messageidentifier/batteryleveldidchange.md)
- [batteryStateDidChange](foundation/notificationcenter/messageidentifier/batterystatedidchange.md)
- [orientationDidChange](foundation/notificationcenter/messageidentifier/orientationdidchange.md)
- [proximityStateDidChange](foundation/notificationcenter/messageidentifier/proximitystatedidchange.md)

### Identifying UIKit document messages

- [stateChanged](foundation/notificationcenter/messageidentifier/statechanged.md)

### Identifying UIKit pasteboard messages

- [changed](foundation/notificationcenter/messageidentifier/changed-28zxj.md)
- [removed](foundation/notificationcenter/messageidentifier/removed.md)

### Identifying UIKit responder messages

- [keyboardWillChangeFrame](foundation/notificationcenter/messageidentifier/keyboardwillchangeframe.md)
- [keyboardDidChangeFrame](foundation/notificationcenter/messageidentifier/keyboarddidchangeframe.md)
- [keyboardWillHide](foundation/notificationcenter/messageidentifier/keyboardwillhide.md)
- [keyboardDidHide](foundation/notificationcenter/messageidentifier/keyboarddidhide.md)
- [keyboardWillShow](foundation/notificationcenter/messageidentifier/keyboardwillshow.md)
- [keyboardDidShow](foundation/notificationcenter/messageidentifier/keyboarddidshow.md)

### Identifying UIKit screen messages

- [brightnessDidChange](foundation/notificationcenter/messageidentifier/brightnessdidchange.md)
- [modeDidChange](foundation/notificationcenter/messageidentifier/modedidchange.md)
- [capturedDidChange](foundation/notificationcenter/messageidentifier/captureddidchange.md)
- [referenceDisplayModeStatusDidChange](foundation/notificationcenter/messageidentifier/referencedisplaymodestatusdidchange.md)

### Identifying UIKit text field messages

- [textDidBeginEditing](foundation/notificationcenter/messageidentifier/textdidbeginediting-7lt1k.md)
- [textDidChange](foundation/notificationcenter/messageidentifier/textdidchange-9363k.md)
- [textDidEndEditing](foundation/notificationcenter/messageidentifier/textdidendediting-4r8fw.md)

### Identifying UIKit text input mode messages

- [currentInputModeDidChange](foundation/notificationcenter/messageidentifier/currentinputmodedidchange.md)

### Identifying UIKit text view messages

- [textDidBeginEditing](foundation/notificationcenter/messageidentifier/textdidbeginediting-9y8tn.md)
- [textDidChange](foundation/notificationcenter/messageidentifier/textdidchange-8ns63.md)
- [textDidEndEditing](foundation/notificationcenter/messageidentifier/textdidendediting-6cmke.md)

### Identifying UIKit view controller messages

- [didBecomeVisible](foundation/notificationcenter/messageidentifier/didbecomevisible.md)
- [didBecomeHidden](foundation/notificationcenter/messageidentifier/didbecomehidden.md)
- [showDetailTargetDidChange](foundation/notificationcenter/messageidentifier/showdetailtargetdidchange.md)

### Identifying UIKit focus messages

- [movementDidFail](foundation/notificationcenter/messageidentifier/movementdidfail.md)

### Identifying UIKit pointer lock state messages

- [didChange](foundation/notificationcenter/messageidentifier/didchange-7wty5.md)

### Identifying UIKit scene messages

- [systemProtectionDidChange](foundation/notificationcenter/messageidentifier/systemprotectiondidchange.md)
- [willConnect](foundation/notificationcenter/messageidentifier/willconnect.md)
- [willEnterForeground](foundation/notificationcenter/messageidentifier/willenterforeground-992xq.md)
- [didActivate](foundation/notificationcenter/messageidentifier/didactivate.md)
- [willDeactivate](foundation/notificationcenter/messageidentifier/willdeactivate.md)
- [didEnterBackground](foundation/notificationcenter/messageidentifier/didenterbackground-5fqw0.md)

### Identifying AppKit workspace messages

- [didHideApplication](foundation/notificationcenter/messageidentifier/didhideapplication.md)
- [didUnhideApplication](foundation/notificationcenter/messageidentifier/didunhideapplication.md)
- [willLaunchApplication](foundation/notificationcenter/messageidentifier/willlaunchapplication.md)
- [didLaunchApplication](foundation/notificationcenter/messageidentifier/didlaunchapplication.md)
- [willSleep](foundation/notificationcenter/messageidentifier/willsleep.md)
- [didWake](foundation/notificationcenter/messageidentifier/didwake.md)
- [didTerminateApplication](foundation/notificationcenter/messageidentifier/didterminateapplication.md)
- [didMountVolume](foundation/notificationcenter/messageidentifier/didmountvolume.md)
- [willUnmountVolume](foundation/notificationcenter/messageidentifier/willunmountvolume.md)
- [didUnmountVolume](foundation/notificationcenter/messageidentifier/didunmountvolume.md)
- [didActivateApplication](foundation/notificationcenter/messageidentifier/didactivateapplication.md)
- [didDeactivateApplication](foundation/notificationcenter/messageidentifier/diddeactivateapplication.md)
- [didRenameVolume](foundation/notificationcenter/messageidentifier/didrenamevolume.md)
- [sessionDidBecomeActive](foundation/notificationcenter/messageidentifier/sessiondidbecomeactive.md)
- [sessionDidResignActive](foundation/notificationcenter/messageidentifier/sessiondidresignactive.md)
- [didChangeFileLabels](foundation/notificationcenter/messageidentifier/didchangefilelabels.md)
- [screensDidSleep](foundation/notificationcenter/messageidentifier/screensdidsleep.md)
- [screensDidWake](foundation/notificationcenter/messageidentifier/screensdidwake.md)
- [activeSpaceDidChange](foundation/notificationcenter/messageidentifier/activespacedidchange.md)
- [accessibilityDisplayOptionsDidChange](foundation/notificationcenter/messageidentifier/accessibilitydisplayoptionsdidchange.md)
- [shouldBeginSuppressingHighDynamicRangeContent](foundation/notificationcenter/messageidentifier/shouldbeginsuppressinghighdynamicrangecontent.md)
- [shouldEndSuppressingHighDynamicRangeContent](foundation/notificationcenter/messageidentifier/shouldendsuppressinghighdynamicrangecontent.md)

### Identifying EventKit messages

- [changed](foundation/notificationcenter/messageidentifier/changed-50yz5.md)

### Identifying iTunes library messages

- [didChange](foundation/notificationcenter/messageidentifier/didchange-1coqh.md)

### Type Properties

- [accessoryDidConnect](foundation/notificationcenter/messageidentifier/accessorydidconnect.md)
- [accessoryDidDisconnect](foundation/notificationcenter/messageidentifier/accessorydiddisconnect.md)
- [boundsDidChange](foundation/notificationcenter/messageidentifier/boundsdidchange.md)
- [colorDidChange](foundation/notificationcenter/messageidentifier/colordidchange.md)
- [colorSpaceDidChange](foundation/notificationcenter/messageidentifier/colorspacedidchange.md)
- [columnConfigurationDidChange](foundation/notificationcenter/messageidentifier/columnconfigurationdidchange.md)
- [columnDidMove](foundation/notificationcenter/messageidentifier/columndidmove-78e2d.md)
- [columnDidMove](foundation/notificationcenter/messageidentifier/columndidmove-9tkq6.md)
- [columnDidResize](foundation/notificationcenter/messageidentifier/columndidresize-5pxs4.md)
- [columnDidResize](foundation/notificationcenter/messageidentifier/columndidresize-7ktag.md)
- [contextHelpModeDidActivate](foundation/notificationcenter/messageidentifier/contexthelpmodedidactivate.md)
- [contextHelpModeDidDeactivate](foundation/notificationcenter/messageidentifier/contexthelpmodediddeactivate.md)
- [conversationHistoryDidUpdateMessage](foundation/notificationcenter/messageidentifier/conversationhistorydidupdatemessage.md)
- [didAddItem](foundation/notificationcenter/messageidentifier/didadditem.md)
- [didBecomeActive](foundation/notificationcenter/messageidentifier/didbecomeactive-2y311.md)
- [didBecomeActive](foundation/notificationcenter/messageidentifier/didbecomeactive-546kc.md)
- [didBecomeCurrent](foundation/notificationcenter/messageidentifier/didbecomecurrent-9p0n4.md)
- [didBecomeCurrent](foundation/notificationcenter/messageidentifier/didbecomecurrent-9zfc.md)
- [didBecomeInactive](foundation/notificationcenter/messageidentifier/didbecomeinactive.md)
- [didBecomeKey](foundation/notificationcenter/messageidentifier/didbecomekey-3qijm.md)
- [didBecomeKey](foundation/notificationcenter/messageidentifier/didbecomekey-6kgub.md)
- [didBecomeMain](foundation/notificationcenter/messageidentifier/didbecomemain.md)
- [didBeginEditing](foundation/notificationcenter/messageidentifier/didbeginediting.md)
- [didBeginTracking](foundation/notificationcenter/messageidentifier/didbegintracking.md)
- [didChange](foundation/notificationcenter/messageidentifier/didchange-1ebzb.md)
- [didChange](foundation/notificationcenter/messageidentifier/didchange-96f1i.md)
- [didChange](foundation/notificationcenter/messageidentifier/didchange-ywl6.md)
- [didChangeAutomaticCapitalization](foundation/notificationcenter/messageidentifier/didchangeautomaticcapitalization.md)
- [didChangeAutomaticDashSubstitution](foundation/notificationcenter/messageidentifier/didchangeautomaticdashsubstitution.md)
- [didChangeAutomaticInlinePrediction](foundation/notificationcenter/messageidentifier/didchangeautomaticinlineprediction.md)
- [didChangeAutomaticPeriodSubstitution](foundation/notificationcenter/messageidentifier/didchangeautomaticperiodsubstitution.md)
- [didChangeAutomaticQuoteSubstitution](foundation/notificationcenter/messageidentifier/didchangeautomaticquotesubstitution.md)
- [didChangeAutomaticSpellingCorrection](foundation/notificationcenter/messageidentifier/didchangeautomaticspellingcorrection.md)
- [didChangeAutomaticTextCompletion](foundation/notificationcenter/messageidentifier/didchangeautomatictextcompletion.md)
- [didChangeAutomaticTextReplacement](foundation/notificationcenter/messageidentifier/didchangeautomatictextreplacement.md)
- [didChangeBackingProperties](foundation/notificationcenter/messageidentifier/didchangebackingproperties.md)
- [didChangeItem](foundation/notificationcenter/messageidentifier/didchangeitem.md)
- [didChangeOcclusionState](foundation/notificationcenter/messageidentifier/didchangeocclusionstate-5853a.md)
- [didChangeOcclusionState](foundation/notificationcenter/messageidentifier/didchangeocclusionstate-99vn6.md)
- [didChangeScreen](foundation/notificationcenter/messageidentifier/didchangescreen.md)
- [didChangeScreenParameters](foundation/notificationcenter/messageidentifier/didchangescreenparameters.md)
- [didChangeScreenProfile](foundation/notificationcenter/messageidentifier/didchangescreenprofile.md)
- [didChangeSelection](foundation/notificationcenter/messageidentifier/didchangeselection.md)
- [didChangeTypingAttributes](foundation/notificationcenter/messageidentifier/didchangetypingattributes.md)
- [didClose](foundation/notificationcenter/messageidentifier/didclose.md)
- [didConnect](foundation/notificationcenter/messageidentifier/didconnect-2pidr.md)
- [didConnect](foundation/notificationcenter/messageidentifier/didconnect-39qlx.md)
- [didConnect](foundation/notificationcenter/messageidentifier/didconnect-3d7x9.md)
- [didConnect](foundation/notificationcenter/messageidentifier/didconnect-6zuxs.md)
- [didConnect](foundation/notificationcenter/messageidentifier/didconnect-oq29.md)
- [didConnect](foundation/notificationcenter/messageidentifier/didconnect-wf9.md)
- [didDeminiaturize](foundation/notificationcenter/messageidentifier/diddeminiaturize.md)
- [didDisconnect](foundation/notificationcenter/messageidentifier/diddisconnect-127wj.md)
- [didDisconnect](foundation/notificationcenter/messageidentifier/diddisconnect-3p6qi.md)
- [didDisconnect](foundation/notificationcenter/messageidentifier/diddisconnect-5s9vw.md)
- [didDisconnect](foundation/notificationcenter/messageidentifier/diddisconnect-97jtl.md)
- [didDisconnect](foundation/notificationcenter/messageidentifier/diddisconnect-9qi2f.md)
- [didDisconnect](foundation/notificationcenter/messageidentifier/diddisconnect-9ymbl.md)
- [didEndEditing](foundation/notificationcenter/messageidentifier/didendediting.md)
- [didEndLiveMagnify](foundation/notificationcenter/messageidentifier/didendlivemagnify.md)
- [didEndLiveResize](foundation/notificationcenter/messageidentifier/didendliveresize.md)
- [didEndLiveScroll](foundation/notificationcenter/messageidentifier/didendlivescroll.md)
- [didEndSheet](foundation/notificationcenter/messageidentifier/didendsheet.md)
- [didEndTracking](foundation/notificationcenter/messageidentifier/didendtracking.md)
- [didEnterFullScreen](foundation/notificationcenter/messageidentifier/didenterfullscreen.md)
- [didEnterVersionBrowser](foundation/notificationcenter/messageidentifier/didenterversionbrowser.md)
- [didExitFullScreen](foundation/notificationcenter/messageidentifier/didexitfullscreen.md)
- [didExitVersionBrowser](foundation/notificationcenter/messageidentifier/didexitversionbrowser.md)
- [didExpose](foundation/notificationcenter/messageidentifier/didexpose.md)
- [didFinishRestoringWindows](foundation/notificationcenter/messageidentifier/didfinishrestoringwindows.md)
- [didHide](foundation/notificationcenter/messageidentifier/didhide.md)
- [didLiveScroll](foundation/notificationcenter/messageidentifier/didlivescroll.md)
- [didMergeChanges](foundation/notificationcenter/messageidentifier/didmergechanges.md)
- [didMergeChangesAsync](foundation/notificationcenter/messageidentifier/didmergechangesasync.md)
- [didMiniaturize](foundation/notificationcenter/messageidentifier/didminiaturize.md)
- [didMove](foundation/notificationcenter/messageidentifier/didmove.md)
- [didMoveToWritableLocation](foundation/notificationcenter/messageidentifier/didmovetowritablelocation.md)
- [didRemoveItem](foundation/notificationcenter/messageidentifier/didremoveitem-4hapv.md)
- [didRemoveItem](foundation/notificationcenter/messageidentifier/didremoveitem-bimz.md)
- [didResignActive](foundation/notificationcenter/messageidentifier/didresignactive.md)
- [didResignKey](foundation/notificationcenter/messageidentifier/didresignkey-11hzh.md)
- [didResignKey](foundation/notificationcenter/messageidentifier/didresignkey-2dgp0.md)
- [didResignMain](foundation/notificationcenter/messageidentifier/didresignmain.md)
- [didResize](foundation/notificationcenter/messageidentifier/didresize.md)
- [didResizeSubviews](foundation/notificationcenter/messageidentifier/didresizesubviews.md)
- [didSave](foundation/notificationcenter/messageidentifier/didsave.md)
- [didSaveObjectIDs](foundation/notificationcenter/messageidentifier/didsaveobjectids.md)
- [didSaveObjectIDsAsync](foundation/notificationcenter/messageidentifier/didsaveobjectidsasync.md)
- [didSendAction](foundation/notificationcenter/messageidentifier/didsendaction.md)
- [didShow](foundation/notificationcenter/messageidentifier/didshow.md)
- [didStopBeingCurrent](foundation/notificationcenter/messageidentifier/didstopbeingcurrent-2sc31.md)
- [didStopBeingCurrent](foundation/notificationcenter/messageidentifier/didstopbeingcurrent-9pdq9.md)
- [didUnhide](foundation/notificationcenter/messageidentifier/didunhide.md)
- [didUpdate](foundation/notificationcenter/messageidentifier/didupdate-p3fm.md)
- [didUpdate](foundation/notificationcenter/messageidentifier/didupdate-vu3m.md)
- [didUpdateWindows](foundation/notificationcenter/messageidentifier/didupdatewindows.md)
- [eventChanged](foundation/notificationcenter/messageidentifier/eventchanged.md)
- [fontSetChanged](foundation/notificationcenter/messageidentifier/fontsetchanged.md)
- [frameDidChange](foundation/notificationcenter/messageidentifier/framedidchange.md)
- [indexDidUpdate](foundation/notificationcenter/messageidentifier/indexdidupdate.md)
- [itemDidCollapse](foundation/notificationcenter/messageidentifier/itemdidcollapse.md)
- [itemDidExpand](foundation/notificationcenter/messageidentifier/itemdidexpand.md)
- [itemWillCollapse](foundation/notificationcenter/messageidentifier/itemwillcollapse.md)
- [itemWillExpand](foundation/notificationcenter/messageidentifier/itemwillexpand.md)
- [keyboardSelectionDidChange](foundation/notificationcenter/messageidentifier/keyboardselectiondidchange.md)
- [objectsDidChange](foundation/notificationcenter/messageidentifier/objectsdidchange.md)
- [preferredScrollerStyleDidChange](foundation/notificationcenter/messageidentifier/preferredscrollerstyledidchange.md)
- [protectedDataDidBecomeAvailable](foundation/notificationcenter/messageidentifier/protecteddatadidbecomeavailable-3di2c.md)
- [protectedDataDidBecomeAvailable](foundation/notificationcenter/messageidentifier/protecteddatadidbecomeavailable-6h44m.md)
- [protectedDataWillBecomeUnavailable](foundation/notificationcenter/messageidentifier/protecteddatawillbecomeunavailable-1izcs.md)
- [protectedDataWillBecomeUnavailable](foundation/notificationcenter/messageidentifier/protecteddatawillbecomeunavailable-3n08h.md)
- [radioAccessTechnologyDidChange](foundation/notificationcenter/messageidentifier/radioaccesstechnologydidchange.md)
- [registrationsChanged](foundation/notificationcenter/messageidentifier/registrationschanged.md)
- [registryDidChange](foundation/notificationcenter/messageidentifier/registrydidchange.md)
- [remoteChange](foundation/notificationcenter/messageidentifier/remotechange.md)
- [resumptionRecommendation](foundation/notificationcenter/messageidentifier/resumptionrecommendation.md)
- [rowsDidChange](foundation/notificationcenter/messageidentifier/rowsdidchange.md)
- [selectedAlternativeString](foundation/notificationcenter/messageidentifier/selectedalternativestring.md)
- [selectionDidChange](foundation/notificationcenter/messageidentifier/selectiondidchange-2akj4.md)
- [selectionDidChange](foundation/notificationcenter/messageidentifier/selectiondidchange-676mh.md)
- [selectionDidChange](foundation/notificationcenter/messageidentifier/selectiondidchange-72x2p.md)
- [selectionDidChange](foundation/notificationcenter/messageidentifier/selectiondidchange-7qmnc.md)
- [selectionIsChanging](foundation/notificationcenter/messageidentifier/selectionischanging-2i647.md)
- [selectionIsChanging](foundation/notificationcenter/messageidentifier/selectionischanging-5u4tc.md)
- [selectionIsChanging](foundation/notificationcenter/messageidentifier/selectionischanging-abh0.md)
- [storesDidChange](foundation/notificationcenter/messageidentifier/storesdidchange.md)
- [storesDidChangeAsync](foundation/notificationcenter/messageidentifier/storesdidchangeasync.md)
- [systemColorsDidChange](foundation/notificationcenter/messageidentifier/systemcolorsdidchange.md)
- [tagsDidChange](foundation/notificationcenter/messageidentifier/tagsdidchange.md)
- [textDidBeginEditing](foundation/notificationcenter/messageidentifier/textdidbeginediting-45vc.md)
- [textDidChange](foundation/notificationcenter/messageidentifier/textdidchange-5j4s4.md)
- [textDidEndEditing](foundation/notificationcenter/messageidentifier/textdidendediting-5yxiy.md)
- [textMessageAvailabilityDidChange](foundation/notificationcenter/messageidentifier/textmessageavailabilitydidchange.md)
- [tokensDidExpire](foundation/notificationcenter/messageidentifier/tokensdidexpire.md)
- [userPreferencesDidChange](foundation/notificationcenter/messageidentifier/userpreferencesdidchange.md)
- [willAddItem](foundation/notificationcenter/messageidentifier/willadditem.md)
- [willBecomeActive](foundation/notificationcenter/messageidentifier/willbecomeactive.md)
- [willBeginSheet](foundation/notificationcenter/messageidentifier/willbeginsheet.md)
- [willChangeNotifyingTextView](foundation/notificationcenter/messageidentifier/willchangenotifyingtextview.md)
- [willClose](foundation/notificationcenter/messageidentifier/willclose-2wsvs.md)
- [willClose](foundation/notificationcenter/messageidentifier/willclose-4565q.md)
- [willDismiss](foundation/notificationcenter/messageidentifier/willdismiss.md)
- [willEnterFullScreen](foundation/notificationcenter/messageidentifier/willenterfullscreen.md)
- [willEnterVersionBrowser](foundation/notificationcenter/messageidentifier/willenterversionbrowser.md)
- [willExitFullScreen](foundation/notificationcenter/messageidentifier/willexitfullscreen.md)
- [willExitVersionBrowser](foundation/notificationcenter/messageidentifier/willexitversionbrowser.md)
- [willFinishLaunching](foundation/notificationcenter/messageidentifier/willfinishlaunching.md)
- [willHide](foundation/notificationcenter/messageidentifier/willhide.md)
- [willMiniaturize](foundation/notificationcenter/messageidentifier/willminiaturize.md)
- [willMove](foundation/notificationcenter/messageidentifier/willmove.md)
- [willPopUp](foundation/notificationcenter/messageidentifier/willpopup-4czk2.md)
- [willPopUp](foundation/notificationcenter/messageidentifier/willpopup-81zuu.md)
- [willPopUp](foundation/notificationcenter/messageidentifier/willpopup-8ycpp.md)
- [willResignActive](foundation/notificationcenter/messageidentifier/willresignactive-9aumz.md)
- [willResizeSubviews](foundation/notificationcenter/messageidentifier/willresizesubviews.md)
- [willSave](foundation/notificationcenter/messageidentifier/willsave.md)
- [willSendAction](foundation/notificationcenter/messageidentifier/willsendaction.md)
- [willShow](foundation/notificationcenter/messageidentifier/willshow.md)
- [willStartLiveMagnify](foundation/notificationcenter/messageidentifier/willstartlivemagnify.md)
- [willStartLiveResize](foundation/notificationcenter/messageidentifier/willstartliveresize.md)
- [willStartLiveScroll](foundation/notificationcenter/messageidentifier/willstartlivescroll.md)
- [willTerminate](foundation/notificationcenter/messageidentifier/willterminate-1u238.md)
- [willTerminate](foundation/notificationcenter/messageidentifier/willterminate-7lu3s.md)
- [willUnhide](foundation/notificationcenter/messageidentifier/willunhide.md)
- [willUpdateWindows](foundation/notificationcenter/messageidentifier/willupdatewindows.md)

## Relationships

### Conforming Types

- [NotificationCenter.BaseMessageIdentifier](foundation/notificationcenter/basemessageidentifier.md)

## See Also

### Using message identifiers

- [NotificationCenter.BaseMessageIdentifier](foundation/notificationcenter/basemessageidentifier.md)