IM-based chat encapsulation based on MQTTClient

//init

• (instancetype)initMQTTWith:(NSString *)strName;

//send message

• (void)sendMessageWith:(NSString *)strMessage WithTpoic:(NSString *)strTopic WithSendUserName:(NSString *)strName;

//disConnect

• (void)disMQTTConnect;

//addTopic

• (void)addTopicWithName:(NSString *)strTopic isGroup:(BOOL)isGroup;

//removeTopic

• (void)deleteTopicWithName:(NSString *)strTopic isGroup:(BOOL)isGroup;