RtcState

状态值

状态	说明
CONNECTING	连接中
CONNECTED	已连接
DISCONNECTED	连接断开
FAILED	连接失败
CLOSED	连接已关闭
SWITCHING	切换中
SWITCHED	切换成功
DESTROYED	已销毁

状态转换

CONNECTING → CONNECTED → DISCONNECTED → CLOSED
    ↓            ↓
  FAILED       SWITCHING → SWITCHED → ...