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paperh18648 margl-907 margr0 margt0 margb0 fi0 ri0 ql sb0 f1 fs24 Copyright f3 'e3f1 1994 by NeXT Computer, Inc. All Rights Reserved.
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fs36 NSCountedSet
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fs28 f0 b fs24 Inherits From:tab b0 fs28 f1 NSMutableSet : NSSet : NSObject
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fs28 s6 f0 b fs24 Conforms To:tab b0 fs28 f1 NSCoding, NSCopying, NSMutableCopying (NSSet)
fi0 NSObject (NSObject)
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fs28 s7 fi-2771 f0 b fs24 Declared In:tab b0 fs28 f1 Foundation/NSSet.h
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fs28 Class Description
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fs28 The NSCountedSet class declares the programmatic interface to an object that manages a mutable set of objects. NSCountedSet provides support for the mathematical concept of a i counted seti0 . A counted set, both in its mathematical sense and in the OpenStep implementation of NSCountedSet, is an unordered collection of elements, just as in a regular set, but the elements of the set aren'27t necessarily distinct. In the literature, a counted set is also knownas a i bagi0 .
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fs28 Each new'd0that is, distinct'd0object inserted into an NSCountedSet object has a counter associated with it. NSCountedSet keeps track of the number of times objects are inserted and requires that objects are removed the same number of times. OpenStep also provides the NSSet class for sets whose elements i arei0 distinct'd0that is, there is only one instance of an object in an NSSet even if the object has been added to the set multiple times.
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fs28 Use set objects as an alternative to array objects when the order of elements is not important, but performance in testing whether an object is contained in the set i isi0 a consideration'd0while arrays are ordered, testing for membership is slower than with sets.
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fs28 Objects in a set must respond to b hashb0 and b isEqual:b0 methods. See the NSObject protocol for details on b hashb0 and b isEqual:b0 . Each new distinct object must provide a unique hash value.
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fs28 Generally, you instantiate an NSCountedSet object by sending one of the b set'bcb0 methods to the NSCountedSet class object, as described in NSSet. These methods return an NSCountedSet object containing the elements (if any) you pass in as arguments. Newly created instances of NSCountedSet created by invoking the b setb0 method can be populated with objects using any of the b init'bcb0 methods. b initWithObjects::b0 is the designated initializer for this class.
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fs28 pard s8 li7029 fi-6552 ri1007 ql tx6652 tx7030 You add or remove objects from a counted set using the b addObject:b0 and b removeObject:b0 methods.
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fs28 An NSCountedSet may be queried using the b objectEnumeratorb0 method, which provides for traversing elements of the set one by one. The b countForObject: b0 method returns the number of times the specified object has been added to this setb .
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fs28 Initializing an NSCountedSet
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fs28 fi-6552 {f3 -} (id)b initWithArray:b0 (NSArray *)i anArrayi0 tab Initializes a newly allocated set object by placing in it the objects contained in i anArray.
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fs28 fi-6552 {f3 -} (id)b initWithCapacity:b0 (unsigned int)i numItemsi0 tab Initializes a newly allocated set object, giving it enough memory to hold i numItemsi0 objects.
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fs28 fi-6552 {f3 -} (id)b initWithSet:b0 (NSSet *)i anotherSeti0 tab Initializes a newly allocated set object by placing in it the objects contained in i anotherSet.
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fs28 Adding Objectstab
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fs28 fi-6552 {f3 -} (void)b addObject:b0 (id)i anObjecti0 tab Adds i anObjecti0 to the set, unless i anObject i0 is equal to some object already in the set. In either case, the counter that'27s returned by b countForObject:b0 is incremented.
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fs28 Removing Objects
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fs28 fi-6552 {f3 -} (void)b removeObject:b0 (id)i anObjecti0 tab Decrements the counter for the object, if the set contains an object that'27s equal to i anObjecti0 . If this causes the counter to reach zero, the object that'27s equal to i anObjecti0 is removed from the set.
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fs28 Querying the NSCountedSet
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fs28 fi-6552 {f3 -} (unsigned int)b countForObject:b0 (id)i anObjecti0 tab Returns the number of times that an object equal to i anObjecti0 has ostensibly been added to the set. (This number is incremented by b addObject: b0 and decremented by b removeObject:b0 .)
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fs28 fi-6552 {f3 -} (NSEnumerator *)b objectEnumeratorb0 tab Returns an enumerator object that will access each object in the set only once, regardless of its count.
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