前提是我没有接离线语音合成， wifi环境播放语音合成，一切正常，断网语音中断，但是我切换到WiFi环境，执行[[BDSSpeechSynthesizer sharedInstance] speakSentence:sentence withError:&err];再重新合成语音，一直报错，下面是错误日志：

Domain=BDTTSErrDomainEmbeddedTTS Code=13828094 "Embedded engine is not initialized (This error may be a follow up to a previous failed attempt to load offline engine)" UserInfo={NSLocalizedDescription=Embedded engine is not initialized (This error may be a follow up to a previous failed attempt to load offline engine)}..13828094

请问怎么破?

急急急......