title: Change AVSpeechUtterance rate in real time
body: <p>I am currently developing an iOS app that converts text to speech using AVSynthesizer.</p>
  
  <p>What I want to do is that while the synthesizer is speaking, utterance rate can be changed and with a slider and the speed of the speaking changes.</p>
  
  <p>I am doing this in the IBAction of the slider:
  self.utterance = sender.value</p>
  
  <p>but the synthesizer doesn't change the speed. I've been looking for information but I haven't found something yet.
  What cand I do? Thanks in advance.</p>