字典的基本概念和常用方法

字典使用Key-Value的形式储存数据。
字典中的对象储存没有顺序，使用key来表示每个对象。
cocoa框架中的字典：NSDictionary和NSMutableDictionary
NSMutableDictionary是NSictionary的子类，能使用其所有方法。
NSMutableDictionary是NSDictionary的可修改版本

 1 #import
 2 int main(int argc, const char * argv[])
 3 {
 4     @autoreleasepool {
 5         //不可变字典NSDictionary
 6         //字典的创建
 7         NSDictionary *dic1=[NSDictionary dictionaryWithObject:@"velue" forKey:@"k1"];//一个键 一个值
 8         NSDictionary *dic2=[NSDictionary dictionaryWithObjectsAndKeys:@"v1",@"k1",@"v2",@"k2",@"v3",@"k3",@"v4",@"k4",@"v5",@"k5",nil];//创建多个键 多个值
 9         NSDictionary *dic3=[NSDictionary dictionaryWithDictionary:dic1];//直接把dic内容给dic3
10         NSLog(@"dic1:%@",dic1);
11         NSLog(@"dic2:%@",dic2);
12         NSLog(@"dic3:%@",dic3);
13         
14         //获取字典的数量
15         int count=[dic2 count];
16         NSLog(@"%d",count);
17         //获取k3的value
18         NSString *string=[dic2 objectForKey:@"k3"];
19         NSLog(@"value:%@",string);
20         
21         //获取字典中所有的key和value
22         NSArray *keyArray=[dic2 allKeys];
23         NSArray *valueArry=[dic2 allValues];
24         NSLog(@"keyArray:%@valueArry:%@",keyArray,valueArry);
25         
26         
27         ////////////////////////////
28         //可变字典NSMutableDictionary
29         NSMutableDictionary *mutableDic1=[NSMutableDictionary dictionaryWithObjectsAndKeys:@"v1",@"k1",@"v2",@"k2",@"v3",@"k3",@"v4",@"k4",@"v5",@"k5", nil];
30         //上面是类方法直接赋值 下面是实例方法开辟空间并赋值
31         NSMutableDictionary *mutableDic=[[NSMutableDictionary alloc]initWithObjectsAndKeys:@"v1",@"k1",@"v2",@"k2",@"v3",@"k3",@"v4",@"k4",@"v5",@"k5", nil];
32         
33         //将一个字典中的velue和key添加到另外一个字典中
34         NSDictionary *dic4=[NSDictionary dictionaryWithObject:@"v6" forKey:@"k6"];
35         [mutableDic addEntriesFromDictionary:dic4];
36         NSLog(@"MutableDic%@",mutableDic);
37         
38         //向字典中添加新的velue和key
39         [mutableDic setValue:@"object" forKey:@"key"];
40         NSLog(@"%@",mutableDic);
41         
42         
43         //创建一个空的字典数组
44         NSMutableDictionary *mutableDic2=[NSMutableDictionary dictionary];
45         [mutableDic2 setDictionary:mutableDic];//
46         NSLog(@"dic2:%@",mutableDic2);
47         
48         //通过制定key删除
49         [mutableDic2 removeObjectForKey:@"k4"];
50         NSLog(@"dic2:%@",mutableDic2);
51         
52         //删除多个键值
53         NSArray *keys=[NSArray arrayWithObjects:@"k1",@"k2",@"k3", nil];
54         [mutableDic2 removeObjectsForKeys:keys];
55         NSLog(@"dic2:%@",mutableDic2);
56         
57         
58         //删除全部键值
59         //        [mutableDic2 removeAllObjects];
60         //        NSLog(@"dic2:%@",mutableDic2);
61         
62         
63         //遍历字典  一般的方法
64         for (int index=0;index<[mutableDic1 count]; index++) {
65             NSString *object=[mutableDic1 objectForKey:[[mutableDic1 allKeys]objectAtIndex:index]];
66             NSLog(@"object:%@",object);
67         }
68         //快速枚举
69         NSLog(@"____________________");
70         for (NSString *key in mutableDic1) {
71             NSString *object=[mutableDic1 objectForKey:key];
72             NSLog(@"object:%@",object);
73         }
74         NSLog(@"____________________");
75         //使用枚举类型
76         NSEnumerator *enumerator=[mutableDic1 keyEnumerator];
77         id key;
78         while(key=[enumerator nextObject]){
79             id object=[mutableDic1 objectForKey:key];
80             NSLog(@"object:%@",object);
81             
82         }
83     }
84     return 0;
85 }

来源：http://blog.sina.com.cn/s/blog_b6e3f37101019luc.html

posted on 2013-11-29 10:32 猿人谷阅读(643) 评论(0) 编辑收藏举报