joinChannel method
加入频道
token
如果为 null 则会采用非安全模式.
id
用户id, 不能为 0
Implementation
Future<int> joinChannel(String token, String channelName, int uid) async {
assert(channelName != null);
assert(uid != null);
IntValue reply = await _api.joinChannel(JoinChannelRequest()
..token = token
..channelName = channelName
..uid = uid);
return reply.value;
}