release method
void
release()
释放连接
Implementation
void release() {
YTLog.i('YTIM.release');
_connectState = IMConnectState.IDLE;
_streamController?.sink.add(IMConnectState.IDLE);
_needReconnect = false;
_channel?.sink.close();
_streamController?.close();
_streamController = null;
_singleton = null;
}