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

　　

 #import <Foundation/Foundation.h>

 int main(int argc , const char *argv[]){
     @autoreleasepool{
         NSDictionary *dicti1 = [NSDictionary     dictionaryWithObjectsAndKeys:@"zhangsan",@"",@"lisi",@"",@"wangwu",@"", nil];
         NSEnumerator *keynum = [dicti1 keyEnumerator];
         for(NSString *key in keynum)
             NSLog(@"key = %@ , value = %@",key,[dicti1 objectForKey:key]);

         NSLog(@"----------------------------");
         NSDictionary *dicti2 = [[NSDictionary alloc]initWithObjectsAndKeys:@"zhangsan",@"",@"lisi",@"",@"wangwu",@"", nil];
         keynum = [dicti2 keyEnumerator];
         for(NSString *key in keynum)
             NSLog(@"key = %@ , value = %@",key,[dicti2 objectForKey:key]);

         NSLog(@"----------------------------");
         NSDictionary *dicti3 = @{@"":@"zhangsan",@"":@"lisi",@"":@"wangwu"};
         keynum = [dicti3 keyEnumerator];
         for(NSString *key in keynum)
             NSLog(@"key = %@  , value = %@",key,[dicti3 objectForKey:key]);

         NSLog(@"------------------------------");
         NSArray *keyarray = @[@"",@"",@""];
         NSArray *valuearray = @[@"zhangsan",@"lisi",@"wangwu"];
         NSDictionary *dicti4 = [NSDictionary dictionaryWithObjects:valuearray forKeys:keyarray];
         keynum = [dicti4 keyEnumerator];
         for(NSString *key in keynum)
             NSLog(@"key = %@ , value = %@",key,[dicti4 objectForKey:key]);

     }
     return ;
 }

　　

　　2）字典的遍历

　　

 #import <Foundation/Foundation.h>

 int main(int argc , const char *argv[]){
     @autoreleasepool {
         NSDictionary *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"",@"lisi",@"",@"wangwu",@"", nil];
         NSEnumerator *number = [dicti keyEnumerator];
         for(NSString *key in number)
             NSLog(@"key = %@ , value = %@",key,[dicti objectForKey:key]);

         NSLog(@"----------------------------");
         NSArray *keyarray = [dicti allKeys];
         for(NSString *key in keyarray)
             NSLog(@"key = %@ , value = %@",key,[dicti objectForKey:key]);

         NSLog(@"-----------------------------");
         for(NSString *key in  dicti)
             NSLog(@"key = %@ , value = %@",key,[dicti objectForKey:key]);

         NSLog(@"-----------------------------");
         [dicti enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
             NSLog(@"key = %@  ,value = %@",key,obj);
         }];
     }
　　　　return 0;
 }

3)  文件的读取

 #import <Foundation/Foundation.h>

 int main(int argc , const char *argv[]){
     @autoreleasepool {
         NSDictionary *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"",@"lisi",@"",@"wangnwu",@"",nil];

         NSString *filename = @"dicti.txt";
         BOOL iswrite = [dicti writeToFile:filename atomically:YES];
         if(iswrite)
             NSLog(@"write to file ok");
         else
             NSLog(@"write to file error");

         NSDictionary *dicti2 = [NSDictionary dictionaryWithContentsOfFile:filename];
         NSLog(@"dicti2 = %@",dicti2);

     }
　　　　return 0;
 }

　　4） 查找

　　

 #import <Foundation/Foundation.h>

 int main(int argc , const char *argv[])
 {
     @autoreleasepool {
         NSDictionary  *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"",@"lisi",@"",@"wangwu",@"",@"zhangsan",@"",nil];

         NSArray *keyarray = [dicti allKeys];     // 查找所有键值
         NSLog(@"%@",keyarray);

         NSArray *valuearray = [dicti allValues];  // 查找所有值
         NSLog(@"%@",valuearray);

         NSString *value = [dicti objectForKey:@""];   // 按键值查找
         NSLog(@"value = %@",value);

         value = dicti[@""];
         NSLog(@"value = %@",value);

         NSArray *keyarray2 = @[@"",@"",@""];    // 利用数组的方式查找
         NSArray *vlauearray2 = [dicti objectsForKeys:keyarray2 notFoundMarker:@"nil"];
         NSLog(@"vlauearray2 = %@",vlauearray2);

         NSArray *keyarray3 = [dicti allKeysForObject:@"zhangsan"];
         NSLog(@"keyarray3 = %@",keyarray3);

         NSDictionary *dicti2 = [dicti dictionaryWithValuesForKeys:keyarray2];
         NSLog(@"dicti2 = %@",dicti2);
     }
     return ;
 }

5) 排序

　　

 #import <Foundation/Foundation.h>

 int main(int argc,char **argv){
     @autoreleasepool {
         NSDictionary *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"",@"lisi",@"",@"wangwu",@"",@"zhangsan",@"",nil];
         NSLog(@"dicti = %@",dicti);

         NSDictionary *dicti2 = [NSDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@,@"lisi",@,@"wangu",@, nil];
         NSLog(@"dicti2 = %@",dicti2);

         NSArray *array = [dicti2 keysSortedByValueUsingSelector:@selector(compare:)];
         for(NSNumber *key in array)
             NSLog(@"key = %@,value = %@",key,dicti2[key]);
     }
     return ;
 }

　　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：

　　

 #import <Foundation/Foundation.h>

 int main(int argc,char **argv){
     @autoreleasepool {
         NSMutableDictionary *mdicti = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"zhangsan",@"",@"lisi",@"",@"wangwu",@"",nil];

         [mdicti setValue:@"zhaoliu" forKey:@""];    // 如果 key 不存在就添加，key 存在就修改
         NSLog(@"mdicti = %@",mdicti);

         [mdicti setValue:@"zzz" forKey:@""];
         NSLog(@"mdicti = %@",mdicti);

         mdicti[@""] = @"bbb";
         NSLog(@"mdicti = %@",mdicti);

         NSDictionary *dicti = [NSDictionary dictionaryWithObjectsAndKeys:@"aaa",@"",@"bbb",@"",@"ccc",@"",nil];
         [mdicti addEntriesFromDictionary:dicti];
         NSLog(@"dicti = %@",mdicti);

         [mdicti removeObjectForKey:@""];     // 删除
         NSLog(@"mdicti = %@",mdicti);

         NSArray *array = @[@"",@"",@""];
         [mdicti removeObjectsForKeys:array];
         NSLog(@"mdicti = %@",mdicti);

         [mdicti removeAllObjects];  // 删除所有的
         NSLog(@"%@",mdicti);
     }
     return ;
 }