Object-C-NSDictionary

存储对象都必须是id(对象类型)不能使基础类型

NSDictionary *scores=[[NSDictionary alloc]initWithObjectsAndKeys:@"89",@"english",@"70",@"computer",nil];

*scores=[[NSDictionary alloc]initWithObjectsAndKeys:[NSNumber numberWithInt:89],@"english"];

scores=[NSDictionary dictionaryWithObjectsAndKeys:]用法与initWithObjectsAndKeys;

NSNumber *englishScore=[scores objectForKey:@"english"];

集合的遍历

方法一

for(NSString *key int socres)

{

// 通过每个元素的key访问value

NSLog(@"%@:%d",key,[[score objetForKey:key] intValue]);

}

方法二

[socres enumerateKeysAndObjectsUsingBloc:^(id key, id obj,BOOL *stop)

{

NSNumber *num=(NSNumber *)obj;

NSLog(@"%@:%d",key,[num intValue]);

}

方法三

NSArray *keysArray = [scores allKeys];

for(int i=0; i<[scores count]; i++)

{

NSLog(@"%@:%d",[keysArray objectAtIndex:i);

NSLog(@"")----;

}

字典排序

NSArray *keysArray=[scores keysSortedByValueUsingSelector:@selector(compare:)];

 1 字典：
 2         //key 一般使用字符串
 3         //value 可以使用任意对象类型
 4 //        NSDictionary *scores = [[NSDictionary alloc]initWithObjectsAndKeys:@"89",@"english",@"70",@"computer", nil];
 5 //
 6 //        NSLog(@"%@",scores);
 7         
 8         NSDictionary *scores2=[NSDictionary dictionaryWithObjectsAndKeys:
 9         [NSNumber numberWithInt:89],@"english",
10         [NSNumber numberWithInt:92],@"maths",
11         [NSNumber numberWithInt:70],@"computer"
12                                , nil];
13         
14 //        NSLog(@"%ld",[scores2 count]);
15 //        NSLog(@"%@",scores2);
16         NSNumber *englishScores = [scores2 objectForKey:@"english"];
17         NSLog(@"%@",englishScores);
18         NSLog(@"%d",[englishScores intValue]);
19 //        //遍历方法1：for in
20         for (NSString *key in scores2) {
21             //通过每个元素的key访问value
22             NSLog(@"%@:%d",key,[[scores2 objectForKey:key] intValue]);
23         }
24 //         //遍历方法2：for
25         NSArray *keysArray = [scores2 allKeys];
26         for (int i=0; i<[scores2 count]; i++) {
27             NSString *key = [keysArray objectAtIndex:i];
28             NSLog(@"%@:%d",key,[[scores2 objectForKey:key]intValue]);
29         }
30 //
31         //排序
32         NSArray *keys = [scores2 keysSortedByValueUsingSelector:@selector(compare:)];
33         NSLog(@"%@",keys);
34     }
35     return 0;

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