The mechanism used to transmit data to other peers.
The data is sent continuously until it is successfully received by the intended recipients or the connection times out.reliable transmissions are delivered in the order they were sent. use this when you need to guarantee delivery.available in ios 3.0 and later.declared in gkpublicconstants.h.
The data is sent once and is not sent again if a transmission error occurred.data transmitted unreliably may be received out of order by recipients. use this for small packets of data that must arrive quickly to be useful to the recipient.available in ios 3.0 and later.declared in gkpublicconstants.h.