AVSpeechSynthesizer doesn't work on iOS10

Question

My AVSpeechSynthesizer code is not working on device (iOS 10), but it worked on iOS 9.x and it is working now in simulator.

let str = self.audioOutput //just some string here, this string exists, and it's in english
let synth = AVSpeechSynthesizer()
let utterance = AVSpeechUtterance(string: str)
    utterance.rate = AVSpeechUtteranceDefaultSpeechRate
let lang = "en-US"

utterance.voice = AVSpeechSynthesisVoice(language: lang)
synth.speakUtterance(utterance)

I'm getting this error:

MobileAssetError:1] Unable to copy asset attributes
Could not get attribute 'LocalURL': Error Domain=MobileAssetError Code=1 "Unable to copy asset attributes"
UserInfo={NSDescription=Unable to copy asset attributes}
0x1741495e0 Copy assets attributes reply: XPC_TYPE_DICTIONARY  <dictionary: 0x1741495e0> { count = 1, transaction: 0, voucher = 0x0, contents =
"Result" => <int64: 0x1744203a0>: 1}

Before that there were error messages like that:

Unable to copy asset information from https://mesu.apple.com/assets/ for asset type

Does anyone know how to solve this issue? I know there is some workarounds (user has to go to Settings->General and switch Speak Selection, for example) but I don't think it's a real solution here.

Update: I created a new project (XCode8/Swift3/no other pods/frameworks and so on). It works in simulator, but it gives me the same errors on my device.

Update 2: It works on device. I have similar error messages (Unable to copy asset attributes and so on), but it works for now. I don't know what it was.

Answer 1

Turn off your silent mode (the physical switch). It works in my case.