当应用程序变为后台时,我的日志中会显示以下消息：

AVSpeechSynthesizer Audio interruption notification: {
    AVAudioSessionInterruptionTypeKey = 1;
}

我在singleton的init方法中初始化了AVSpeechSynthesizer：

self.speechSynthesizer = [[AVSpeechSynthesizer alloc] init];
    self.speechSynthesizer.delegate = self;

我说这样的话语：

AVSpeechUtterance *utt = [[AVSpeechUtterance alloc] initWithString:dialogue];
utt.voice = [AVSpeechSynthesisVoice voiceWithLanguage:voice];

utt.pitchMultiplier = pitch;
utt.rate = rate;
utt.preUtteranceDelay = preDelay;
utt.postUtteranceDelay = postDelay;
utt.volume = volumeSetting;

[self.speechSynthesizer speakUtterance:utt];

iOS 8上有没有人见过这样的东西？