Looking for in depth tutorial on SFSpeechRecognizer

it's a great tool from Apple, but I want to delve more into its engine as I need to. The documentation doesn't seem to go there. For instance, I can't figure out how to clear the bestTranscritption object in speechRecognizer, as it always contains the entire transcription. There are other things I would like to work with as well.

Has anyone worked with this heavily enough to recommend proper books are paid for tutorials?

Many thanks

Looking for in depth tutorial on SFSpeechRecognizer
 
 
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