NSCharacterSet

Inherits From: NSObject

Conforms To: NSCoding, NSCopying, NSMutableCopying NSObject (NSObject)

Declared In: Foundation/NSCharacterSet.h

Class Description

The NSCharacterSet class declares the programmatic interface to objects that construct immutable descriptions of character sets in the Unicode character encoding. Using NSCharacterSet objects, you can determine if a given Unicode character belongs to a specified set. See NSMutableCharacterSet for a class that constructs descriptions of character sets that can be modified dynamically. NSCharacterSet's primitive methods are characterIsMember: and bitmapRepresentation. Subclasses of NSCharacterSet must implement these two methods.

NSCharacterSet objects can be thought of as loosely analogous to the is1/4 macros (such as isupper())available in the ctype collection of most standard C libraries. NSCharacterSet objects, however, offer much greater flexibility in that you can dynamically construct your own custom character sets against which you can test characters.

The term bitmap in the descriptions below does not refer to bitmap characters in the sense of screen fonts for display. The bitmaps referred to here are compact ordered bit set representations of Unicode character positions or ranges of Unicode characters.

You create standard character setssuch as a set of alphanumerics, or a set of decimal digitsby invoking the NSCharacterSet class object with one of the methods described in Creating a Standard Character Set. These methods provide convenient means to create a standard set without needing to specify the character positons explicitly.

You can also create your own custom character sets by using one of the methods described under Creating a Custom Character Set. To create a character set with multiple disjoint ranges, see the add1/4 methods described in NSMutableCharacterSet.

Creating a Standard Character Set

• + (NSCharacterSet *)alphanumericCharacterSet Returns a character set containing the uppercase and lowercase alphabetic characters (a-z, A-Z, other alphabetic characters such as [[Yacute]], ‰, Û, ‡, and so on) and the decimal digit characters (0-9).
• + (NSCharacterSet *)controlCharacterSet Returns a character set containing the control characters (characters with decimal Unicode values 0 to 31 and 127 to 159).
• + (NSCharacterSet *)decimalDigitCharacterSet Returns a character set containing only decimal digit characters (0-9).
• + (NSCharacterSet *)decomposableCharacterSet Returns a character set containing all individual Unicode characters that can also be represented as composed character sequences.
• + (NSCharacterSet *)illegalCharacterSet Returns a character set containing the illegal Unicode values.
• + (NSCharacterSet *)letterCharacterSet Returns a character set containing the uppercase and lowercase alphabetic characters (a-z, A-Z, other alphabetic characters such as [[Yacute]], ‰, Û, ‡, and so on).
• + (NSCharacterSet *)lowercaseLetterCharacterSet Returns a character set containing only lowercase alphabetic characters (a-z, other alphabetic characters such as [[Yacute]], Û, and so on).
• + (NSCharacterSet *)nonBaseCharacterSet Returns a set containing all characters which are not defined to be base characters for purposes of dynamic character composition.
• + (NSCharacterSet *)uppercaseLetterCharacterSet Returns a character set containing only uppercase alphabetic characters (A-Z, other alphabetic characters such as ‰, ‡, and so on).
• + (NSCharacterSet *)whitespaceAndNewlineCharacterSet Returns a character set containing only whitespace characters (space and tab) and the newline character.
• + (NSCharacterSet *)whitespaceCharacterSet Returns a character set containing only in-line whitespace characters (space and tab). This set doesn't contain the newline or carriage return characters.

• + (NSCharacterSet *)characterSetWithBitmapRepresentation:(NSData *)data Returns a character set containing characters determined by the bitmap representation data.
• + (NSCharacterSet *)characterSetWithCharactersInString:(NSString *)aString Returns a character set containing the characters in aString. If aString is empty, an empty character set is returned. aString must not be nil.
• + (NSCharacterSet *)characterSetWithRange:(NSRange)aRange Returns a character set containing characters whose Unicode values are given by aRange.

• - (NSData *)bitmapRepresentation Returns an NSData object encoding the receiving character set in binary format. This format is suitable for saving to a file or otherwise transmitting or archiving.

• - (BOOL)characterIsMember:(unichar)aCharacter Returns YES if aCharacter is in the receiving character set, NO if it isn't.

• - (NSCharacterSet *)invertedSet Returns a character set containing only characters that don't exist in the receiver.