I\'ve read in several books... and online... about immutable and mutable strings. They claim \"immutable strings\" can\'t be changed. (But they never define \"change\".)
The answer is - none. Immutable means it cannot be changed into anything different than the original string. Every character stays the same, the length cannot change, etc. Once it's defined you cannot change anything about that string. If you want to make it longer or shorter or change any of the characters, you need to make a new string (or use a NSMutableString to begin with).