转NSDictionary类使用

字典：NSDictionary

 

字典就是关键字及其定义（描述）的集合。Cocoa中的实现字典的集合NSDictionary在给定的关键字（通常是一个NSString）下存储一个数值（可以是任何类型的对象）。然后你就可以用这个关键字来查找相应的数值。
不同于数组，字典（也被称为散列表或关联数组）使用的是键查询的优化存储方式。它可以立即找出要查询的数据，而不需要遍历整个数组进行查找。
可使用dictionaryWithObjectsAndKeys来创建字典
查询字典的值：objectForKey
NSMutableDictionary的dictionary方法可以创建一个可变字典，也可以使用dictionaryWithCapaticy：。
使用 setObject:forkey: 方法添加字典元素，如果关键字已存在，则用新植替换旧值。
类似的，NSMutableDictionary类允许随意添加或删除字典元素。
添加元素：setObject:forkey:
删除元素：removeObjectForKey:
Example:

 1 //
 2  //  MyClass.h
 3  //  FoundationKit4
 4  //
 5  //  Created by Elf Sundae on 10/22/10.
 6 //  Copyright 2010 Control-Strength. All rights reserved.
 7 //
 8 
 9 #import <Cocoa/Cocoa.h>
10 
11 
12 @interface MyClass : NSObject
13 {
14     NSString *firstName;
15     NSString *lastName;
16 }
17 
18 
19 - (void) setFirstName:(NSString *)m_firstName;
20 - (NSString *) firstName;
21 
22 - (void) setLastName: (NSString *) m_lastName;
23 - (NSString *) lastName;
24 
25 
26 @end

 

 1 //
 2 //  MyClass.m
 3 //  FoundationKit4
 4 //
 5 //  Created by Elf Sundae on 10/22/10.
 6 //  Copyright 2010 Control-Strength. All rights reserved.
 7 //
 8 
 9 #import "MyClass.h"
10 
11 
12 @implementation MyClass
13 
14 - (void) setFirstName:(NSString *)m_firstName{
15    
16     firstName = m_firstName;
17 }
18 - (NSString *) firstName{
19  return firstName;
20 }
21 
22 - (void) setLastName: (NSString *) m_lastName{
23     lastName = m_lastName;
24 }
25 - (NSString *) lastName{
26  return lastName;
27 }
28 
29 
30 - (NSString *) description
31 {   
32  if (firstName == nil || lastName == nil) {
33  return @"No Name found.";
34     } else {
35  return [NSString stringWithFormat:@"%@ %@",
36             firstName,lastName];
37     }
38    
39 }
40 
41 @end

 

 1 /*
 2  * 示例字典（NSDictionary,NSMutableDictionary）操作
 3  *
 4  * Elf Sundae  10/22/2010
 5  */
 6 
 7 #import <Foundation/Foundation.h>
 8 #import "MyClass.h"
 9 
10 int main (int argc, const char * argv[]) {
11     NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
12    
13  // 创建字典：dictionaryWithObjectsAndKeys:
14     MyClass *my1 = [MyClass new];
15     MyClass *my2 = [MyClass new];
16     MyClass *my3 = [MyClass new];
17     MyClass *my4 = [MyClass new];
18    
19     NSDictionary *myClassDict;
20     myClassDict = [NSDictionary dictionaryWithObjectsAndKeys:
21               my1, @"my1",
22               my2, @"my2",
23               my3, @"my3",
24               my4, @"my4", nil];
25  // 获取值 objectForKey
26     MyClass *sub = [myClassDict objectForKey: @"my3"];
27  if (sub == nil) {
28         exit(1);
29     }
30     [sub setFirstName:@"Elf"];
31     [sub setLastName:@"Sundae"];
32    
33     NSLog(@"修改数据： %@",sub);
34    
35  // 遍历字典
36     NSLog(@"***遍历字典myClassDict如下：");
37  for (id key in myClassDict)
38     {
39         NSLog(@"key: %@ ,value: %@",key,[myClassDict objectForKey:key]);
40     }
41     NSLog(@"***遍历字典myClassDict结束。");
42    
43  // MARK: ***  添加新元素  ***   
44  // NSDictionary无法添加或删除元素，可以使用NSMutableDictionary.
45     NSMutableDictionary *myNewDict = [NSMutableDictionary dictionary];
46  // 将原有字典添加到新字典的一对元素
47  //[myNewDict setObject:myClassDic forKey:@"旧的不可变字典myClassDic"];
48    
49  // 遍历添加已有数据(原字典)
50  for (id key in myClassDict)
51     {
52         [myNewDict setObject: [myClassDict objectForKey:key]
53                   forKey:key];
54     }
55    
56     NSString *newkey = @"newKey";
57     NSString *newValue = @"This is a new Value.";
58     [myNewDict setObject:newValue forKey:newkey];
59    
60  // 遍历myNewDict
61     NSLog(@"***遍历字典myNewDict如下：");
62  for (id key in myNewDict)
63     {
64         NSLog(@"key: %@ ,value: %@",key,[myNewDict objectForKey:key]);
65     }
66     NSLog(@"***遍历字典myNewDict结束。");
67    
68  // 删除元素
69     [myNewDict removeObjectForKey: @"newKey"];
70    
71  // 遍历myNewDict
72     NSLog(@"***遍历字典myNewDict如下：");
73  for (id key in myNewDict)
74     {
75         NSLog(@"key: %@ ,value: %@",key,[myNewDict objectForKey:key]);
76     }
77     NSLog(@"***遍历字典myNewDict结束。");
78    
79     [pool drain];
80  return 0;
81 }

 

 

// 输出结果（省略日期 时间等信息）
修改数据： Elf Sundae
***遍历字典myClassDict如下：
key: my3 ,value: Elf Sundae
key: my4 ,value: No Name found.
key: my1 ,value: No Name found.
key: my2 ,value: No Name found.
***遍历字典myClassDict结束。
***遍历字典myNewDict如下：
key: newKey ,value: This is a new Value.
key: my3 ,value: Elf Sundae
key: my4 ,value: No Name found.
key: my1 ,value: No Name found.
key: my2 ,value: No Name found.
***遍历字典myNewDict结束。
***遍历字典myNewDict如下：
key: my3 ,value: Elf Sundae
key: my4 ,value: No Name found.
key: my1 ,value: No Name found.
key: my2 ,value: No Name found.
***遍历字典myNewDict结束。