OC语言基础之NSDictionary
1.NSDictionary字典的创建
1: // key value
2: // key -==> value
3: NSDictionary *dict = [NSDictionary dictionaryWithObject:@"v" forKey:@"key"];
4:
5: NSArray *keys = [NSArray arrayWithObjects:@"k1", @"k2", nil];
6: NSArray *values = [NSArray arrayWithObjects:@"v1", @"v2", nil];
7: NSDictionary *dict1 = [NSDictionary dictionaryWithObjects:values
8: forKeys:keys];
9: NSDictionary *dict2 = [NSDictionary dictionaryWithObjectsAndKeys:@"v", @"key",
10: @"v1", @"key1",
11: nil];
12: NSLog(@"%@", dict2);
13:
14:
15: // BOOL isSuccess = [dict writeToFile:@"/Users/apple/Desktop/1.txt"
16: // atomically:YES];
17: // if (isSuccess) {
18: // NSLog(@"成功");
19: // }else{
20: // NSLog(@"写入失败");
21: // }
22:
23: NSDictionary *dict3 = [NSDictionary dictionaryWithContentsOfFile:@"/Users/apple/Desktop/1.txt"];
24: NSLog(@"%@", dict3);
字典的遍历
1: NSDictionary *pDict = [NSDictionary dictionaryWithObjectsAndKeys:@"abc", @"name",
2: @"11", @"age",
3: @"男", @"gender",
4: nil];
5: // NSArray *keys = [pDict allKeys];
6: // for (int i = 0; i<[pDict count]; i++) {
7: // NSString *key = [keys objectAtIndex:i];
8: // NSString *value = [pDict objectForKey:key];
9: // NSLog(@"%@: value= %@", key, value);
10: // }
11:
12: // for (id key in pDict) {
13: // NSLog(@"%@", key);
14: // }
15: //
16:
17: [pDict enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
18: NSLog(@"%@", key);
19:
20: // 修改stop指向内存的值
21: *stop = YES;
22: }];
2.可变字典
1:
2: NSMutableDictionary *dictM = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"v", @"key",
3: nil];
4: [dictM setObject:@"1" forKey:@"key"];
5: NSLog(@"%@", dictM);
3.具体使用的例子
1: // 名字
2: // 年龄
3: // 性别
4: NSDictionary *pDict = [NSDictionary dictionaryWithObjectsAndKeys:
5: @"11", @"age",
6: @"abc", @"name",
7: @"男", @"gender",
8: nil];
9:
10:
11: // NSMutableArray *array = [NSMutableArray array];
12: // [array addObject:pDict];
13:
14: id name = [pDict objectForKey:@"name"];
15: NSLog(@"%@", name);
4.各常用类对比
1: /*
2: 集合
3: 1.NSArray\NSMutableArray
4: * 有序
5: * 快速创建（不可变）：@[obj1, obj2, obj3]
6: * 快速访问元素：数组名[i]
7:
8: 2.NSSet\NSMutableSet
9: * 无序
10:
11: 3.NSDictionary\NSMutableDictionary
12: * 无序
13: * 快速创建（不可变）：@{key1 : value1, key2 : value2}
14: * 快速访问元素：字典名[key]
15: */
例子
1: /*
2: 字典：
3:
4: key ----> value
5: 索引 ----> 文字内容
6:
7: 里面存储的东西都是键值对
8:
9:
10: */
11:
12: // NSDictionary *dict = [NSDictionary dictionaryWithObject:@"jack" forKey:@"name"];
13:
14:
15: // NSArray *keys = @[@"name", @"address"];
16: // NSArray *objects = @[@"jack", @"北京"];
17:
18: // NSDictionary *dict = [NSDictionary dictionaryWithObjects:objects forKeys:keys];
19:
20:
21: /*
22: NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
23: @"jack", @"name",
24: @"北京", @"address",
25: @"32423434", @"qq", nil];*/
26:
27:
28: NSDictionary *dict = @{@"name" : @"jack", @"address" : @"北京"};
29:
30: // id obj = [dict objectForKey:@"name"];
31:
32: id obj = dict[@"name"];
33:
34: NSLog(@"%@", obj);
35:
36:
37:
38: // 返回的是键值对的个数
39: NSLog(@"%ld", dict.count);
