NSDictionary可以接受NSSet作为键吗？ [英] Can a NSDictionary take in NSSet as key?

问题描述

我知道你可以使用任何对象作为NSDictionary的关键，但问题是它能够检索正确的值吗？支持我有一个条目，其中key = {1,3,5}和value = {@hello}。我能通过传入集合{3,5,1}从这个字典条目检索吗？

I know you can use any object as key for NSDictionary but the problem is will it be able to retrieve the correct value? Support I have an entry where the key = {1,3,5} and value = { @"hello" }. Will I be able to retrieve from this dictionary entry by passing in the set {3,5,1}?

按顺序，是基于指针匹配的键，还是它实际上比较集合的内容？ （如果是前者，我该如何解决这个问题？）

In order words, is the key matched based on the pointer or does it actually compare the contents of the set? (And if it is the former, how can I overcome this?)

推荐答案

有任何陷阱）。

NSMutableDictionary * dict = [NSMutableDictionary dictionary];

NSSet * set;
set = [NSSet setWithObjects:@"a", @"b", @"c", @"d", nil];
[dict setObject:@"1" forKey:set];

set = [NSSet setWithObjects:@"b", @"c", @"d", @"e", nil];
[dict setObject:@"2" forKey:set];

id key;
NSEnumerator * enumerator = [dict keyEnumerator];
while ((key = [enumerator nextObject]))
    NSLog(@"%@ : %@", key, [dict objectForKey:key]);

set = [NSSet setWithObjects:@"c", @"b", @"e", @"d", nil];
NSString * value = [dict objectForKey:set];
NSLog(@"set: %@ : key: %@", set, value);

输出：

2009-12-08 15:42:17.885 x[4989] (d, e, b, c) : 2
2009-12-08 15:42:17.887 x[4989] (d, a, b, c) : 1
2009-12-08 15:42:17.887 x[4989] set: (d, e, b, c) : key: 2

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