【黑马程序员】【Foundation框架】字典NSDictionary和NSMutableDictionary

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字典由键-值对组成的数据集合

4种创建字典方式

1>针对单个键值对直接赋值

 1  NSDictionary *dic = [NSDictionary dictionaryWithObject:@"dajie" forKey:@"name"];//直接创建字典 2     id object = [dic objectForKey:@"name"];// 取出name键对应值 3     NSLog(@"%@",object);

2>以键值对集合创建

1       NSArray *obj = @[@"dajie",@"ly"];2       NSArray *keys = @[@"name",@"address"];3       NSDictionary *dic1 = [NSDictionary dictionaryWithObjects:obj forKeys:keys];//创建字典4       NSLog(@"%@",dic1);

3>直接创建并赋值

1      NSDictionary *dic2 = [NSDictionary dictionaryWithObjectsAndKeys:@"dajie",@"name",@"ly",@"address", nil];//nil不可少2      NSLog(@"\n---%@",dic2);

3      id obj2 = [dic2 objectForKey:@"name"];//根据键取出对应的值4      NSLog(@"%@",obj2);

4>开发中常用

　　　　//xcode 新特性 开发中常用15     NSDictionary *dic3 = @{@"name" : @"dajie",@"address":@"ly",@"qq":@"12324124"};16     NSLog(@"%@\n--%@--%ld",dic3,[dic3 objectForKey:@"name"],dic3.count);

可变字典

2      NSMutableDictionary *mdic = [NSMutableDictionary dictionary];//创建

添加元素和删除元素

//添加键值对20     [mdic setObject:@"dajie" forKey:@"person"];21     [mdic setObject:@"hashiqi" forKey:@"dog"];22     [mdic setObject:@"shapi" forKey:@"dog"];  //主键一样字典元素前者会被后者覆盖23     NSString *str = mdic[@"dog"];24     NSLog(@"%@",str);25   //删除26     [mdic removeAllObjects];27     [mdic removeObjectForKey:@"dog"];28     NSLog(@"%@",mdic);

遍历元素

1基本for循环遍历

30  　　NSDictionary *newDic = @{31                              @"name": @"dajie",32                              @"dog":@"HASHIQI"　　　　};33     NSArray *key = [newDic allKeys];//取出所有的key34     for (int i;  i < newDic.count; i++) {35         NSString *keys = key[i];36         NSString *value = newDic[keys];37         NSLog(@"%@ = %@",keys,value);38     }

2 简洁遍历

//推荐使用 快速遍历40     [newDic enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {41         NSLog(@"%@ - %@ ",key ,obj );42     }];

总结

/* NSArray 相当于java List;// NSSet相当于java Set // NSdictionary相当于java Map // NSArray NSMutableArray有序 快速访问 @[obj1,obj2,obj3];快速访问元素 数组名[i];// NSSet NSMutableSet无序// NSDictionary NSMutableDictionary 无序 快速创建@{key1 : value1,key2 : value2};快速访问 字典名[key];*/

 1     NSArray *persons = @[ 2 @{@"name" :@"dajie",@"phone":@"1234353", 3   @"books" : @[@"5分钟编程ios",@"5分钟编程Android"]}, 4 @{@"name" :@"xiaojie",@"phone":@"2234353"}, 5   @{@"name" :@"jinyu",@"phone":@"3234353",@"age" : @"1.2"} 6                          ]; 7     // 先取出数组位置对应的字典 8     // 再根据字典name这个key找到对应的值 9 //    NSLog(@"%@",persons[1][@"name"]);10 //      NSLog(@"%@",persons[0][@"books"]);11     12     for (NSString *arrays in persons) {13 //     NSInteger *lines  = [persons indexOfObject:@"name"];14 //        NSLog(@"%ld - %@",lines,arrays);15         NSLog(@" %@ ",arrays);16     }

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