String message = textEditingController.value.text;
    Imclient.sendMessage(_curConversion, TextMessageContent(message),
    successCallback: (messageUid,timestamp){
      print("消息发送成功$messageUid;$timestamp");
    }, errorCallback: (errorCode){
      print("消息发送失败$errorCode");
    }).then((value) {
      //Android端这里返回的消息是null
      if(Platform.isIOS){
        messageList.insert(0, value);
        textEditingController.clear();
        _scrollToListBottom();
      }
    });