NSCharacterSet Class Reference

Inherits from NSObject Conforms to NSCoding
NSCopying
NSMutableCopying
NSObject (NSObject) Framework /System/Library/Frameworks/Foundation.framework Availability Available in iOS 2.0 and later. Companion guide String Programming Guide Declared in NSCharacterSet.h
NSURL.h Related sample code Advanced UISearchBar KMLViewer MVCNetworking SimpleURLConnections Using NSXMLParser to parse XML documents

Overview

An NSCharacterSet object represents a set of Unicode-compliant characters. NSString and NSScanner objects use NSCharacterSet objects to group characters together for searching operations, so that they can find any of a particular set of characters during a search. The cluster’s two public classes, NSCharacterSet andNSMutableCharacterSet, declare the programmatic interface for static and dynamic character sets, respectively.

The objects you create using these classes are referred to as character set objects (and when no confusion will result, merely as character sets). Because of the nature of class clusters, character set objects aren’t actual instances of the NSCharacterSet or NSMutableCharacterSet classes but of one of their private subclasses. Although a character set object’s class is private, its interface is public, as declared by these abstract superclasses, NSCharacterSet and NSMutableCharacterSet. The character set classes adopt the NSCopying and NSMutableCopying protocols, making it convenient to convert a character set of one type to the other.

The NSCharacterSet class declares the programmatic interface for an object that manages a set of Unicode characters (see the NSString class cluster specification for information on Unicode). NSCharacterSet’s principal primitive method, characterIsMember:, provides the basis for all other instance methods in its interface. A subclass of NSCharacterSet needs only to implement this method, plus mutableCopyWithZone:, for proper behavior. For optimal performance, a subclass should also override bitmapRepresentation, which otherwise works by invoking characterIsMember: for every possible Unicode value.

NSCharacterSet is “toll-free bridged” with its Core Foundation counterpart, CFCharacterSetRef. See “Toll-Free Bridging” for more information on toll-free bridging.

The mutable subclass of NSCharacterSet is NSMutableCharacterSet.

Adopted Protocols

NSCoding

• encodeWithCoder:

• initWithCoder:

  NSCopying

  • copyWithZone:

    NSMutableCopying

    • mutableCopyWithZone:

      Tasks

      Creating a Standard Character Set

      • + alphanumericCharacterSet
      • + capitalizedLetterCharacterSet
      • + controlCharacterSet
      • + decimalDigitCharacterSet
      • + decomposableCharacterSet
      • + illegalCharacterSet
      • + letterCharacterSet
      • + lowercaseLetterCharacterSet
      • + newlineCharacterSet
      • + nonBaseCharacterSet
      • + punctuationCharacterSet
      • + symbolCharacterSet
      • + uppercaseLetterCharacterSet
      • + whitespaceAndNewlineCharacterSet
      • + whitespaceCharacterSet
        

        Creating a Character Set for URL Encoding

        • + URLFragmentAllowedCharacterSet
        • + URLHostAllowedCharacterSet
        • + URLPasswordAllowedCharacterSet
        • + URLPathAllowedCharacterSet
        • + URLQueryAllowedCharacterSet
        • + URLUserAllowedCharacterSet
          

          Creating a Custom Character Set

          • + characterSetWithCharactersInString:
          • + characterSetWithRange:
          • C invertedSet
            

            Creating and Managing Character Sets as Bitmap Representations

            • + characterSetWithBitmapRepresentation:
            • + characterSetWithContentsOfFile:
            • C bitmapRepresentation
              

              Testing Set Membership

              • C characterIsMember:
              • C hasMemberInPlane:
              • C isSupersetOfSet:
              • C longCharacterIsMember:
                

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