There are some means to chain commands together. Simple ones like just a ; or more complex ones like logical chains which run depending on some conditions. The third one is piping commands, which effectively hands over the output data to the next command in the chain.
MKBlockQueue allows you to create a chain of blocks and execute them one after the other in a queue. Compared with NSOperation, with MKBlockQueue you decide yourself when a block is complete and when you want the queue to continue. You can also pass data from one block to the next.