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:89],@"english",
        [NSNumber numberWithInt:92],@"maths",
        [NSNumber numberWithInt:70],@"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=0; 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 0;

ie