Objective-c 字典对象

　　oc 中的 NSDictionary 的作用同 java 中的字典类相同，提供了 “键－值”对的组合。比如，是用字典类实现对学生姓名和学号的存放，编号是一个键（唯一性），姓名是值。它的方法有：

　　下面通过例子来具体说明它的用法：

　　 1）构建字典

 1 #import <Foundation/Foundation.h>
 2 
 3 int main(int argc , const char *argv[]){
 4     @autoreleasepool{
 5         NSDictionary *dicti1 = [NSDictionary     dictionaryWithObjectsAndKeys:@"zhangsan",@"1",@"lisi",@"2",@"wangwu",@"3", nil];
 6         NSEnumerator *keynum = [dicti1 keyEnumerator];
 7         for(NSString *key in keynum)
 8             NSLog(@"key = %@ , value = %@",key,[dicti1 objectForKey:key]);
 9         
10         NSLog(@"----------------------------");
11         NSDictionary *dicti2 = [[NSDictionary alloc]initWithObjectsAndKeys:@"zhangsan",@"1",@"lisi",@"2",@"wangwu",@"3", nil];
12         keynum = [dicti2 keyEnumerator];
13         for(NSString *key in keynum)
14             NSLog(@"key = %@ , value = %@",key,[dicti2 objectForKey:key]);
15         
16         NSLog(@"----------------------------");
17         NSDictionary *dicti3 = @{@"1":@"zhangsan",@"2":@"lisi",@"3":@"wangwu"};
18         keynum = [dicti3 keyEnumerator];
19         for(NSString *key in keynum)
20             NSLog(@"key = %@  , value = %@",key,[dicti3 objectForKey:key]);
21         
22         NSLog(@"------------------------------");
23         NSArray *keyarray = @[@"1",@"2",@"3"];
24         NSArray *valuearray = @[@"zhangsan",@"lisi",@"wangwu"];
25         NSDictionary *dicti4 = [NSDictionary dictionaryWithObjects:valuearray forKeys:keyarray];
26         keynum = [dicti4 keyEnumerator];
27         for(NSString *key in keynum)
28             NSLog(@"key = %@ , value = %@",key,[dicti4 objectForKey:key]);
29         
30     }
31     return 0;
32 }

　　2）字典的遍历

 1 #import <Foundation/Foundation.h>
 2 
 3 int main(int argc , const char *argv[]){
 4     @autoreleasepool {
 5         NSDictionary *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"1",@"lisi",@"2",@"wangwu",@"3", nil];
 6         NSEnumerator *number = [dicti keyEnumerator];
 7         for(NSString *key in number)
 8             NSLog(@"key = %@ , value = %@",key,[dicti objectForKey:key]);
 9         
10         NSLog(@"----------------------------");
11         NSArray *keyarray = [dicti allKeys];
12         for(NSString *key in keyarray)
13             NSLog(@"key = %@ , value = %@",key,[dicti objectForKey:key]);
14         
15         NSLog(@"-----------------------------");
16         for(NSString *key in  dicti)
17             NSLog(@"key = %@ , value = %@",key,[dicti objectForKey:key]);
18         
19         NSLog(@"-----------------------------");
20         [dicti enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
21             NSLog(@"key = %@  ,value = %@",key,obj);
22         }];
23     }
　　　　return 0;
24 }

3) 文件的读取

 1 #import <Foundation/Foundation.h>
 2 
 3 int main(int argc , const char *argv[]){
 4     @autoreleasepool {
 5         NSDictionary *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"1",@"lisi",@"2",@"wangnwu",@"3",nil];
 6         
 7         NSString *filename = @"dicti.txt";
 8         BOOL iswrite = [dicti writeToFile:filename atomically:YES];
 9         if(iswrite)
10             NSLog(@"write to file ok");
11         else
12             NSLog(@"write to file error");
13         
14         NSDictionary *dicti2 = [NSDictionary dictionaryWithContentsOfFile:filename];
15         NSLog(@"dicti2 = %@",dicti2);
16         
17     }
　　　　return 0;
18 }

　　4）查找

 1 #import <Foundation/Foundation.h>
 2 
 3 int main(int argc , const char *argv[])
 4 {
 5     @autoreleasepool {
 6         NSDictionary  *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"1",@"lisi",@"2",@"wangwu",@"3",@"zhangsan",@"4",nil];
 7         
 8         NSArray *keyarray = [dicti allKeys];     // 查找所有键值
 9         NSLog(@"%@",keyarray);
10         
11         NSArray *valuearray = [dicti allValues];  // 查找所有值
12         NSLog(@"%@",valuearray);
13         
14         NSString *value = [dicti objectForKey:@"1"];   // 按键值查找
15         NSLog(@"value = %@",value);
16         
17         value = dicti[@"2"];
18         NSLog(@"value = %@",value);
19         
20         NSArray *keyarray2 = @[@"1",@"2",@"3"];    // 利用数组的方式查找
21         NSArray *vlauearray2 = [dicti objectsForKeys:keyarray2 notFoundMarker:@"nil"];
22         NSLog(@"vlauearray2 = %@",vlauearray2);
23         
24         NSArray *keyarray3 = [dicti allKeysForObject:@"zhangsan"];
25         NSLog(@"keyarray3 = %@",keyarray3);
26         
27         NSDictionary *dicti2 = [dicti dictionaryWithValuesForKeys:keyarray2];
28         NSLog(@"dicti2 = %@",dicti2);
29     }
30     return 0;
31 }

5) 排序

 1 #import <Foundation/Foundation.h>
 2 
 3 
 4 int main(int argc,char **argv){
 5     @autoreleasepool {
 6         NSDictionary *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"2",@"lisi",@"3",@"wangwu",@"1",@"zhangsan",@"4",nil];
 7         NSLog(@"dicti = %@",dicti);
 8         
 9         NSDictionary *dicti2 = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@1,@"lisi",@2,@"wangu",@3, nil];
10         NSLog(@"dicti2 = %@",dicti2);
11         
12         NSArray *array = [dicti2 keysSortedByValueUsingSelector:@selector(compare:)];
13         for(NSNumber *key in array)
14             NSLog(@"key = %@,value = %@",key,dicti2[key]);
15     }
16     return 0;
17 }

　　2. 同样字典对象中也存在可变字典（NSDictionary）,下面我们来通过一个例子来说明它的用法：

　　代码举例：

 1 #import <Foundation/Foundation.h>
 2 
 3 
 4 int main(int argc,char **argv){
 5     @autoreleasepool {
 6         NSMutableDictionary *mdicti = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"1",@"lisi",@"2",@"wangwu",@"3",nil];
 7         
 8         [mdicti setValue:@"zhaoliu" forKey:@"4"];    // 如果 key 不存在就添加，key 存在就修改
 9         NSLog(@"mdicti = %@",mdicti);
10         
11         [mdicti setValue:@"zzz" forKey:@"1"];
12         NSLog(@"mdicti = %@",mdicti);
13         
14         mdicti[@"5"] = @"bbb";
15         NSLog(@"mdicti = %@",mdicti);
16         
17         NSDictionary *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"aaa",@"11",@"bbb",@"12",@"ccc",@"13",nil];
18         [mdicti addEntriesFromDictionary:dicti];
19         NSLog(@"dicti = %@",mdicti);
20         
21         [mdicti removeObjectForKey:@"1"];     // 删除
22         NSLog(@"mdicti = %@",mdicti);
23         
24         NSArray *array = @[@"11",@"12",@"13"];
25         [mdicti removeObjectsForKeys:array];
26         NSLog(@"mdicti = %@",mdicti);
27         
28         [mdicti removeAllObjects];  // 删除所有的
29         NSLog(@"%@",mdicti);
30     }
31     return 0;
32 }