Dictionary的用法

 1 atomically:原子性，当文件内容写入成功之后再创建文件。
 2 
 3 NSArray *keys = [NSArray arrayWithObjects:@"name", @"age", nil];
 4 NSArray *values = [NSArray arrayWithObjects:@"wzx", [NSNumber numberWithInt:16], nil];
 5 NSDictionary *dict = [NSDictionary dictionaryWithObjects:values forKeys:keys];
 6 
 7     // NSDictionary是不可变的
 8    NSDictionary *dict = [NSDictionary dictionaryWithObject:@"v" forKey:@"k"];
 9     
10     // 最常用的初始化方式
11    dict = [NSDictionary dictionaryWithObjectsAndKeys:
12             @"v1", @"k1",
13             @"v2", @"k2",
14             @"v3", @"k3", nil];
15     
16     NSArray *objects = [NSArray arrayWithObjects:@"v1", @"v2", @"v3", nil];
17     NSArray *keys = [NSArray arrayWithObjects:@"k1", @"k2", @"k3", nil];
18     dict = [NSDictionary dictionaryWithObjects:objects forKeys:keys];
19     NSLog(@"%@", dict);
20 
21 
22     NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
23             @"v1", @"k1",
24             @"v2", @"k2",
25             @"v3", @"k3", nil];
26     
27     // count是计算有多少个键值对(key-value)
28     NSLog(@"count=%zi", dict.count);
29     
30     // 由于NSDictionary是不可变的，所以只能取值，而不能修改值
31    id obj = [dict objectForKey:@"k2"];
32     NSLog(@"obj=%@", obj);
33 
34     // 将字典写入文件中
35    NSString *path = @"/Users/apple/Desktop/dict.xml";
36     [dict writeToFile:path atomically:YES];
37     
38     // 从文件中读取内容
39    dict = [NSDictionary dictionaryWithContentsOfFile:path];
40     NSLog(@"dict=%@", dict);
41 
42 
43    NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
44                           @"v1", @"k1",
45                           @"v2", @"k2",
46                           @"v3", @"k3", nil];
47     // 返回所有的key
48     NSArray *keys = [dict allKeys];
49     //NSLog(@"keys=%@", keys);
50     
51     NSArray *objects = [dict allValues];
52     //NSLog(@"objects=%@", objects);
53     
54     // 根据多个key取出对应的多个value
55     // 当key找不到对应的value时，用marker参数值代替
56     objects = [dict objectsForKeys:[NSArray arrayWithObjects:@"k1", @"k2", @"k4", nil] notFoundMarker:@"not-found"];
57     NSLog(@"objects=%@", objects);
58 
59 
60   #pragma mark 遍历字典
61   NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
62                           @"v1", @"k1",
63                           @"v2", @"k2",
64                           @"v3", @"k3", nil];
65     // 遍历字典的所有key
66     for (id key in dict) {
67         id value = [dict objectForKey:key];
68         NSLog(@"%@=%@", key, value);
69     }
70 
71 
72  NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
73                           @"v1", @"k1",
74                           @"v2", @"k2",
75                           @"v3", @"k3", nil];
76     // key迭代器
77     NSEnumerator *enumer = [dict keyEnumerator];
78     id key = nil;
79     while ( key = [enumer nextObject]) {
80         id value = [dict objectForKey:key];
81         NSLog(@"%@=%@", key, value);
82     }
83     
84       // 对象迭代器
85     // [dict objectEnumerator];
86 
87 
88 
89 //block
90  NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
91                           @"v1", @"k1",
92                           @"v2", @"k2",
93                           @"v3", @"k3", nil];
94     [dict enumerateKeysAndObjectsUsingBlock:
95      ^(id key, id obj, BOOL *stop) {
96         NSLog(@"%@=%@", key, obj);
97     }];
98