Apple's Objective-C runtime does a lot of very interesting tricks to make more efficient use of memory. Despite being fundamental types in the language, NSStrin

Apple's Objective-C runtime does a lot of very interesting tricks to make more efficient use of memory. Despite being fundamental types in the language, NSString, NSNumber, NSDictionary and so on are only interacted with via dynamically-linked dynamic dispatch, which gives the runtime a lot of freedom to change their representations without affecting the ABI. For example, contents of strings are sometimes stuffed into tagged pointers rather than being heap-allocated.