Why does Objective C provide both class NSString and subclass NSMutableString rather than just provide NSMutableString? Isn’t a NSString equivalent to “const NSMutableString”?
In C++, you have only one string class, std::string, and if you want a constant you declare a const std:string.
I’m interested in knowing why I shouldn’t just use NSMutableString everywhere and never bother with NSString? There must be a reason, or the language designers wouldn’t provide both. maybe it takes up less storage or something?
The reason for both classes is the same reason that you sometimes use a std::string and sometimes use a const std::string. However, unlike C++, Objective-C doesn’t have const methods, so they instead separate const- from non-const- methods into two different classes. This is also seen in many of the core classes, such as NSArray (NSMutableArray), NSDictionary (NSMutableDictionary), etc.