学步园

dictionaryWithObjectsAndKeys 用来初始化

objectForKey 用来取值

sample：

NSDictionary *testDic=[NSDictionary dictionaryWithObjectsAndKeys:@"1",@"hello",@"2",@"what", nil];

    NSLog(@"val is %@",[testDic objectForKey:@"hello"]);

NSMutableDictionary可变字典NSMutableDictionary继承自NSDictionary

常用api：

dictionaryWithCapacity： 用来初始化

setObject: 设置

removeObjectForKey 删除

[count] 返回字典的数量

[allKeys]获取所有键的集合

[allValues】获取所有值得集合

sample:

        NSMutableDictionary *testDic=[NSMutableDictionary dictionaryWithCapacity:12];
        [testDic setObject:@"1" forKey:@"hel"];
        [testDic setObject:@"2da" forKey:@"what"];
        [testDic setObject:@"hello" forKey:@"hello"];
        NSLog(@"the val is %@",[testDic objectForKey:@"what"]);
        NSLog(@"the length is %ld",[testDic count]);
        [testDic removeObjectForKey:@"hello"];
        NSLog(@"the length is %lu",testDic.count);
        
        NSArray *keyArray=[testDic allKeys];
        NSArray *valArray=[testDic allValues];
        NSLog(@"the all keys are %@",keyArray);
        NSLog(@"the all values are %@",valArray);
    }

返回结果是：

2013-10-09 17:20:19.533 element[401:303] the val is 2da
2013-10-09 17:20:19.535 element[401:303] the length is 3
2013-10-09 17:20:19.536 element[401:303] the length is 2
2013-10-09 17:20:19.537 element[401:303] the all keys are (
    what,
    hel
)
2013-10-09 17:20:19.537 element[401:303] the all values are (
    2da,
    1
)

不经常用的方法为

- (void)addEntriesFromDictionary:(NSDictionary *)otherDictionary;

- (void)removeAllObjects;

- (void)removeObjectsForKeys:(NSArray *)keyArray;

- (void)setDictionary:(NSDictionary *)otherDictionary;

- (void)setObject:(id)obj forKeyedSubscript:(id <NSCopying>)keyNS_AVAILABLE(10_8,
6_0);

sample如下：

        NSMutableDictionary *emptyDic=[NSMutableDictionary dictionary];
        [emptyDic setValue:@"2" forKey:@"2"];
        NSLog(@"empty DIC is %@",emptyDic);
        NSMutableDictionary *testDic=[NSMutableDictionary dictionaryWithObjectsAndKeys:@"hello",@"1",@"andy",@"2",@"yang",@"3",nil];
        
        NSDictionary *dic4=[NSDictionary dictionaryWithObject:@"yang" forKey:@"4"];
        [testDic addEntriesFromDictionary:dic4];
        NSLog(@"the mutalble dictionary is %@",testDic);
        [emptyDic setDictionary:testDic];
        NSLog(@"empty DIC is %@",emptyDic);
        
        NSArray *deleteArr=[NSArray arrayWithObjects:@"1",@"2",@"yang",nil];
        [testDic removeObjectsForKeys:deleteArr];
        NSLog(@"the mutalble dictionary is %@",testDic);
        
        [testDic removeAllObjects];
        NSLog(@"the mutalble dictionary is %@",testDic);

结果：

2013-10-09 17:39:37.832 element[463:303] empty DIC is {
    2 = 2;
}
2013-10-09 17:39:37.834 element[463:303] the mutalble dictionary is {
    1 = hello;
    2 = andy;
    3 = yang;
    4 = yang;
}
2013-10-09 17:39:37.834 element[463:303] empty DIC is {
    1 = hello;
    2 = andy;
    3 = yang;
    4 = yang;
}
2013-10-09 17:39:37.835 element[463:303] the mutalble dictionary is {
    3 = yang;
    4 = yang;
}
2013-10-09 17:39:37.835 element[463:303] the mutalble dictionary is {
}

遍历字典的方法：

for（id key in dic）

{

 id obj=[dic objectForKey:key];

NSLog(@"%@",obj);

}

一般的枚举

        NSMutableDictionary *testDic=[NSMutableDictionary
dictionaryWithObjectsAndKeys:@"hello",@"1",@"andy",@"2",@"yang",@"3",nil];

        for(int index=0;index<[testDic
count];index++)

        {

            NSString *obj=[testDic
objectForKey:[[testDic allKeys] objectAtIndex:index]];

            NSLog(@"the val is %@",obj);

        }

        for(id key
in testDic)

        {

            NSString *obj2=[testDic
objectForKey:key];

            NSLog(@"the val is %@",obj2);

        }