iOS Swift - Text to Speech make the app crash -

i have app text speech feature when clicking on button. code worked fine until made app crash. think bug must related new release of ios 9.3.3 can't find on net that's why i'm posting here.

here function triggered button:

func texttospeech(){    let textsynthesizer = avspeechsynthesizer()    let utterance = avspeechutterance(string: self.targetlanguage)    utterance.voice = avspeechsynthesisvoice(language: self.languageflag)    textsynthesizer.speakutterance(utterance)  } 

when click on button error on avspeechsynthesizer initialisation :

and in console: (lldb)

does has idea of how fix ? thanks, alex