ARC and retain ; summary, what is


 All you have to do is claim ownership of any object you need 
 and remember to relinquish ownership when you’re done with it.


The retain method claims ownership of an existing object.
It’s like telling the operating system,
"Hey! I need that object too, so don’t get rid of it!”
This is a necessary ability when other objects need to make sure
their properties refer to a valid instance.

Note: retain