Advanced MVCS - iOS Programming: The Big Nerd Ranch Guide - page 823

ure 29.5 ) . While it's okay to have a few instances of RSSChannel (it's a pretty small ob-
ject), it's not okay to have double the RSSItem s and suffer through loading the file
twice.
Figure 29.5 Duplicate RSSItems in memory
NSCopying
Fortunately, there is an easier solution. RSSChannel can conform to NSCopying .
When a class conforms to this protocol, you can create copies of its instances by sending