The iOS PDF text-to-speech feature uses Apple APIs to guess the language of the document. By default, the language is automatically detected using a framework function provided by Apple. This works for many documents but sometimes guesses wrong. If you know the language of the document, we suggest setting it manually using the selectedLanguage property of the PSPDFSpeechController, which can be accessed via the shared PSPDFKit configuration instance:

PSPDFKit.sharedInstance.speechController.selectedLanguage = documentLanguage
PSPDFKit.sharedInstance.speechController.selectedLanguage = documentLanguage;

The PSPDFSpeechController has additional properties to control speed rate and pitch.

Text Speech