Question

我有一个从JSON解析的对象数组。我的JSON看起来像这样;

- message: [

   -{
     movie_id: 30,
     movie_name: "Scream",
     category_name: "Horror"

     },
   -{ 
      movie_id: 31,
      movie_name: "Avengers",
      category_name: "Action"

     },
   -{
     movie_id: 32,
     movie_name: "Friday the 13th",
     category_name: "Horror"

     },
   -{ 
      movie_id: 33,
      movie_name: "The ring",
      category_name: "Horror"

     },
   -{
     movie_id: 34,
     movie_name: "Die Hard",
     category_name: "Action"

     },
   -{ 
      movie_id: 35,
      movie_name: "The ring 2",
      category_name: "Horror"

     },
  ....

它是一部包含许多电影的JSON电影数组。我无法做的是解析每个对象并按类别中的category_name排列它们，所以所有的＆＃34;恐怖＆＃34;将被组合在一起，所有动作，以及所有浪漫等等。但是......我需要能够在每个类别的开头放置一个String值。所以数组可能如下所示：

Index
0       "Horror"
1        Movie Object
2        Movie Object
3        Movie Object
4        "Romance"
5        Movie Object
6        Movie Object
7        "Action"
8        Movie Object
9        Movie Object
10       Movie Object

我有以下参数的电影对象;

 NSString *movie_id
 NSString * movie_name
 NSString *category_name

非常感谢任何帮助。

Answer 1

我建议对解析后的数据采用略有不同的结构。

为什么不创建数组的字典（使用类别名称作为键），而不是混合字符串和对象的数组？只需遍历原始的JSON即可。对于每个电影对象，请检查该类别名称是否存在该键。如果没有，请添加一个新数组作为该类别名称的值。然后将影片对象添加到数组中。

你的最后一本字典会是这样的：

@{ @"Horror" : @[obj1, obj2, obj 3], @"Romance" : @[obj4, obj5, obj 6], @"Action" : @[obj7, obj8, obj 9] }

通过这种方式，您可以遍历每个类别，并且还可以遍历电影中的每个类别

Answer 2

假设您有阵列消息，那么您可以将它们排列为

NSArray *categories = [message valueForKeyPath:@"@distinctUnionOfObjects.category_name"];
NSMutableArray *results = [NSMutableArray new];
for (NSString *categoryName in categories)
{
    NSArray *groupArray = [message filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"category_name = %@", categoryName]];
    [results addObject:categoryName];
    [results addObjectsFromArray:groupArray];
}

和你的最终数组我的意思是结果

(
        Horror,
        {
        "category_name" = Horror;
        "movie_id" = 30;
        "movie_name" = Scream;
    },
        {
        " movie_name" = "Friday the 13th";
        "category_name" = Horror;
        "movie_id" = 32;
    },
        {
        "category_name" = Horror;
        "movie_id" = 33;
        "movie_name" = "The ring";
    },
        {
        "category_name" = Horror;
        "movie_id" = 35;
        "movie_name" = "The ring 2";
    },
    Action,
        {
        "category_name" = Action;
        "movie_id" = 31;
        "movie_name" = Avengers;
    },
        {
        "category_name" = Action;
        "movie_id" = 34;
        "movie_name" = "Die Hard";
    }
)

希望这是你想要的。但这不是一个好的编码实践，在同一个数组中有不同的数据类型（字符串和字典）。所以你应该像这样解析它们

NSArray *categories = [message valueForKeyPath:@"@distinctUnionOfObjects.category_name"];
    NSMutableDictionary *results = [NSMutableDictionary new];
    for (NSString *categoryName in categories)
    {
        NSArray *groupArray = [message filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"category_name = %@", categoryName]];
        [results setObject:groupArray forKey:categoryName];
    }

你的结果将是。

{
    Action =     (
                {
            "category_name" = Action;
            "movie_id" = 31;
            "movie_name" = Avengers;
        },
                {
            "category_name" = Action;
            "movie_id" = 34;
            "movie_name" = "Die Hard";
        }
    );
    Horror =     (
                {
            "category_name" = Horror;
            "movie_id" = 30;
            "movie_name" = Scream;
        },
                {
            " movie_name" = "Friday the 13th";
            "category_name" = Horror;
            "movie_id" = 32;
        },
                {
            "category_name" = Horror;
            "movie_id" = 33;
            "movie_name" = "The ring";
        },
                {
            "category_name" = Horror;
            "movie_id" = 35;
            "movie_name" = "The ring 2";
        }
    );
}

现在选择你想要的任何东西。

按对象值对对象数组进行排序

2 个答案: