What does the NS prefix mean?

ios objective-c cocoa cocoa-touch
Martin08 picture Martin08 · Jan 23, 2009 · Viewed 153k times · Source

Many classes in Cocoa/Cocoa Touch have the NS prefix. What does it mean?

Answer

Barry Wark picture Barry Wark · Jan 23, 2009

The original code for the Cocoa frameworks came from the NeXTSTEP libraries Foundation and AppKit (those names are still used by Apple's Cocoa frameworks), and the NextStep engineers chose to prefix their symbols with NS.

Because Objective-C is an extension of C and thus doesn't have namespaces like in C++, symbols must be prefixed with a unique prefix so that they don't collide. This is particularly important for symbols defined in a framework.

If you are writing an application, such that your code is only likely ever to use your symbols, you don't have to worry about this. But if you're writing a framework or library for others' use, you should also prefix your symbols with a unique prefix. CocoaDev has a page where many developers in the Cocoa community have listed their "chosen" prefixes. You may also find this SO discussion helpful.

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