iOS Programming: The Big Nerd Ranch Guide

Copying

There is one more change we need to make to our properties – specifically, the two properties that point to instances of NSString.

In general, when you have a property that points to an instance of a class that has a mutable subclass (like NSString or NSArray), it is safer to make a copy of the object to point to rather than pointing to an existing object that could have other owners.

For instance, imagine if a BNRItem was initialized so that its itemName pointed to an instance of NSMutableString.

N​S​M​u​t​a​b​l​e​S​t​r​i​n​g​ ​*​m​u​t​a​b​l​e​S​t​r​i​n​g​ ​=​ ​[​[​N​S​M​u​t​a​b​l​e​S​t​r​i​n​g​ ​a​l​l​o​c​]​ ​i​n​i​t​]​;​ B​N​R​I​t​e​m​ ​*​i​t​e​m​ ​=​ ​[​[​B​N​R​I​t​e​m​ ​a​l​l​o​c​]​ ​i​n​i​t​W​i​t​h​I​t​e​m​N​a​m​e​:​m​u​t​a​b​l​e​S​t​r​i​n​g​ ...