Any one else noticing that when you have your device language as Spanish and region to US or Latin America, the AVSpeechSynthesisVoice speakes with a Spanish (Spain) accent? Seems like it's not picking the right voice. Ie, she pronounces "cinco" like "thinco".
Bah, nevermind. My app had a "Spanish" localization, but not a "Spanish (Latin America)" localization. When I added the latter in the project settings, it started picking the right voice.