Naming Functions

Objective-C allows you to express behavior through functions as well as methods. You should use functions rather than, say, class methods, when the underlying object is always a singleton or when you are dealing with obviously functional subsystems.

Functions have some general naming rules that you should follow:

• Function names are formed like method names, but with a couple exceptions:

  • They start with the same prefix that you use for classes and constants.

  • The first letter of the word after the prefix is capitalized.

• Most function names start with verbs that describe the effect the function has:

NSHighlightRect

NSDeallocateObject

Functions that query properties have a further set of naming rules:

• If the function returns the property of its first argument, omit the verb.

  unsigned int NSEventMaskFromType(NSEventType type)

  float NSHeight(NSRect aRect)

• If the value is returned by reference, use “Get”.

  const char *NSGetSizeAndAlignment(const char *typePtr, unsigned int *sizep, unsigned int *alignp)

• If the value returned is a boolean, the function should begin with an inflected verb.

  BOOL NSDecimalIsNotANumber(const NSDecimal *decimal)