Do I have that right?
Yes, with the clarification that the dictionary that the grammar is created from is an NSDictionary (as seen in the method parameter) and the dictionary you are passing to startListening is a phonetic dictionary of pronunciations as a text file that is automatically created by OELanguageModelGenerator if it doesn’t return an error at generation time.
Does the crash happen without n-best? I wasn’t aware that n-best was at all compatible with JSGF, but you say that your JSGF works otherwise with your code.
You can get a bit more info out by doing a backtrace on your lldb prompt (typing “bt” at the blue lldb prompt and hitting return). Always helpful to have other logging from your app removed from the logs if possible, since there’s a lot to look at there.