AVSpeechSynthesizerMBS.availableVoicesDidChange

Type	Topic	Plugin	Version	macOS	Windows	Linux	iOS	Targets
event	Speech	MBS AVFoundation Plugin	24.1	✅ Yes	❌ No	❌ No	✅ Yes

An event that indicates a change in available voices for speech synthesis.

The system posts this notification when available voices for speech synthesis on the system change. For example, a new personal voice becomes available and the user authorized the app to access personal voices. Or new 3rd party voices become available through an app the user downloads.

AVSpeechSynthesizerMBS.didCancelSpeechUtterance(utterance as AVSpeechUtteranceMBS)

Type	Topic	Plugin	Version	macOS	Windows	Linux	iOS	Targets
event	Speech	MBS AVFoundation Plugin	24.1	✅ Yes	❌ No	❌ No	✅ Yes

Tells you when the synthesizer cancels speaking an utterance.

utterance: The utterance that the speech synthesizer cancels speaking.

The system only calls this method if a speech synthesizer is speaking an utterance and the system calls its stopSpeakingAtBoundary method. The system doesn’t call this method if the synthesizer is in a delay between utterances when speech stops, and it doesn’t call it for unspoken utterances.

AVSpeechSynthesizerMBS.didContinueSpeechUtterance(utterance as AVSpeechUtteranceMBS)

Type	Topic	Plugin	Version	macOS	Windows	Linux	iOS	Targets
event	Speech	MBS AVFoundation Plugin	24.1	✅ Yes	❌ No	❌ No	✅ Yes

Tells you when the synthesizer resumes speaking an utterance after pausing.

utterance: The utterance that the speech synthesizer resumes speaking.

The system only calls this method if a speech synthesizer pauses speaking and the system calls its pauseSpeakingAtBoundary method. The system doesn’t call this method if the synthesizer pauses while in a delay between utterances.

AVSpeechSynthesizerMBS.didFinishSpeechUtterance(utterance as AVSpeechUtteranceMBS)

Type	Topic	Plugin	Version	macOS	Windows	Linux	iOS	Targets
event	Speech	MBS AVFoundation Plugin	24.1	✅ Yes	❌ No	❌ No	✅ Yes

Tells you when the synthesizer finishes speaking an utterance.

utterance: The utterance that the speech synthesizer finishes speaking.

The system ignores the final utterance’s postUtteranceDelay and calls this method immediately when speech ends.

AVSpeechSynthesizerMBS.didPauseSpeechUtterance(utterance as AVSpeechUtteranceMBS)

Type	Topic	Plugin	Version	macOS	Windows	Linux	iOS	Targets
event	Speech	MBS AVFoundation Plugin	24.1	✅ Yes	❌ No	❌ No	✅ Yes

Tells you when the synthesizer pauses while speaking an utterance.

utterance: The utterance that the speech synthesizer pauses speaking.

The system only calls this method if a speech synthesizer is speaking an utterance and the system calls its pauseSpeakingAtBoundary method. The system doesn’t call this method if the synthesizer is in a delay between utterances when speech pauses.

AVSpeechSynthesizerMBS.didStartSpeechUtterance(utterance as AVSpeechUtteranceMBS)

Type	Topic	Plugin	Version	macOS	Windows	Linux	iOS	Targets
event	Speech	MBS AVFoundation Plugin	24.1	✅ Yes	❌ No	❌ No	✅ Yes

Tells you when the synthesizer begins speaking an utterance.

utterance: The utterance that the speech synthesizer starts speaking.

If the utterance’s preUtteranceDelay property is greater than zero, the system calls this method after the delay completes and speech begins.

AVSpeechSynthesizerMBS.requestPersonalVoiceAuthorizationCompleted(status as Integer)

Type	Topic	Plugin	Version	macOS	Windows	Linux	iOS	Targets
event	Speech	MBS AVFoundation Plugin	24.1	✅ Yes	❌ No	❌ No	✅ Yes

A completion event that the system calls after the user responds to a request to authorize use of personal voices, which receives the authorization status as an argument.

AVSpeechSynthesizerMBS.SpeechSynthesizerBuffer(buffer as AVAudioBufferMBS)

Type	Topic	Plugin	Version	macOS	Windows	Linux	iOS	Targets
event	Speech	MBS AVFoundation Plugin	24.1	✅ Yes	❌ No	❌ No	✅ Yes

The event that receives a buffer of generated speech.

AVSpeechSynthesizerMBS.SpeechSynthesizerMarker(markers() as AVSpeechSynthesisMarkerMBS)

Type	Topic	Plugin	Version	macOS	Windows	Linux	iOS	Targets
event	Speech	MBS AVFoundation Plugin	24.1	✅ Yes	❌ No	❌ No	✅ Yes

The event that receives speech markers.

AVSpeechSynthesizerMBS.willSpeakMarker(marker as AVSpeechSynthesisMarkerMBS, utterance as AVSpeechUtteranceMBS)

Type	Topic	Plugin	Version	macOS	Windows	Linux	iOS	Targets
event	Speech	MBS AVFoundation Plugin	24.1	✅ Yes	❌ No	❌ No	✅ Yes

Tells you when the synthesizer is about to speak a marker of an utterance’s text.

marker: The synthesized audio that the speech synthesizer is about to speak.
utterance: The utterance that the speech synthesizer pauses speaking.

AVSpeechSynthesizerMBS.willSpeakRangeOfSpeechString(characterRange as NSRangeMBS, utterance as AVSpeechUtteranceMBS)

Type	Topic	Plugin	Version	macOS	Windows	Linux	iOS	Targets
event	Speech	MBS AVFoundation Plugin	24.1	✅ Yes	❌ No	❌ No	✅ Yes

Tells you when the synthesizer is about to speak a portion of an utterance’s text.

characterRange: The range of characters in the utterance’s speechString that correspond to the unit of speech the synthesizer is about to speak.
utterance: The utterance that the speech synthesizer is about to speak.

The system calls this method once for each unit of speech in the utterance’s text, which is generally a word.

Tip
Implement this method if you want to provide a user interface to visually highlight each word as the synthesizer speaks it.