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:)];

 字典：
         //key 一般使用字符串
         //value 可以使用任意对象类型
 //        NSDictionary *scores = [[NSDictionary alloc]initWithObjectsAndKeys:@"89",@"english",@"70",@"computer", nil];
 //
 //        NSLog(@"%@",scores);

         NSDictionary *scores2=[NSDictionary dictionaryWithObjectsAndKeys:
         [NSNumber numberWithInt:],@"english",
         [NSNumber numberWithInt:],@"maths",
         [NSNumber numberWithInt:],@"computer"
                                , nil];

 //        NSLog(@"%ld",[scores2 count]);
 //        NSLog(@"%@",scores2);
         NSNumber *englishScores = [scores2 objectForKey:@"english"];
         NSLog(@"%@",englishScores);
         NSLog(@"%d",[englishScores intValue]);
 //        //遍历方法1：for in
         for (NSString *key in scores2) {
             //通过每个元素的key访问value
             NSLog(@"%@:%d",key,[[scores2 objectForKey:key] intValue]);
         }
 //         //遍历方法2：for
         NSArray *keysArray = [scores2 allKeys];
         for (int i=; i<[scores2 count]; i++) {
             NSString *key = [keysArray objectAtIndex:i];
             NSLog(@"%@:%d",key,[[scores2 objectForKey:key]intValue]);
         }
 //
         //排序
         NSArray *keys = [scores2 keysSortedByValueUsingSelector:@selector(compare:)];
         NSLog(@"%@",keys);
     }
     return ;

ie