Different voices in Text to Speech iOS app

Question

I have a Text to Speech App and all is good, but I was looking for a voice.

In Settings/Accessibility/Voice Over/Speech/Voice there is a list of voices. I wanted to select one of those, for example "Susan (Enhanced)". How would I go about doing that?

I am new to Text to Speech and AVSpeechSynthesizer so I was hoping for some advice how to select that voice?

When I try it in General/Settings it sounds good, but when I select, what I thought was that voice it in my App, it sounds different. This happens with all of the voices I tried.

Here is the code I used to speak the text:

    for voice in AVSpeechSynthesisVoice.speechVoices()
    {
        print("\(voice.name)")
        if voice.name == "Susan (Enhanced)" {
            self.voiceToUse = voice
        }
    }

    let textToSpeak = self.tvTextToSpeak.text
    if (!textToSpeak!.isEmpty)
    {
        let speechSynthesizer = AVSpeechSynthesizer()
        let speechUtterance: AVSpeechUtterance = AVSpeechUtterance(string: textToSpeak!)
        speechUtterance.voice = self.voiceToUse
        speechSynthesizer.speak(speechUtterance)
    }

So if I use the same text as the example in the iOS settings it sounds different in my App, why?

1. Is it something I need to do?
2. Are those voices special?
3. Does it have to do with the utterance, I have not set that.

Thanks for any clarification.

Answer 1

Many of the voices, especially the "enhanced" ones, need to be downloaded on the device first. On your device go to Settings->Accessibility->Spoken Content->Voices, and make sure that you download the voice that you're trying to use.

I was able to use "Samantha (Enhanced)", once I downloaded it.

Answer 2

Set speechUtterance.prefersAssistiveTechnologySettings = true to use Spoken content selected voice in your iPhone. And you don't need to specify what voice to use in this case.

A Boolean that specifies whether assistive technology settings take precedence over the property values of this utterance.