How to name a constant in Objective-C?

objective-c naming-conventions constants extern
hpique picture hpique · Oct 30, 2010 · Viewed 13k times · Source

What's the naming convention for constants in Objective-C (or most widely used way to name them)?

Is there a different criteria for extern constants?

Some styles I have seen:

NSString* const kPreferenceFirstRun = @"FirstRun";

// Replace "XY" by a prefix representing your company, project or module
NSString* const XYPreferenceFirstRun = @"FirstRun";

Answer

hpique picture hpique · Oct 31, 2010

After a bit of googling I've found the official coding guidelines for Cocoa.

To sum up:

  • Start with a two- or three-letter prefix in ALL-CAPS
  • Rest in UpperCamelCase
  • Same criteria for extern constants

I agree with itaiferber that the k prefix style is clearer and also much more useful for autocompletion. It would be interesting to know if this style is more popular than the official guidelines.

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