使用Mantle在iOS中解析嵌套的json

Question

I'm trying to parse data received from a service using the framework Mantle. The json has nested data and I am having problems to parse it. The json is like the following:

  {
  "sections": [
    {
      "title": "title1",
      "level": 1,
      "content": [
        {
          "type": "type1",
          "text": "text1"
        }
      ],
      "images": []
    },
    {
      "title": "title2",
      "level": 2,
      "content": [
        {
          "type": "type2",
          "text": "text2"
        },
        {
          "type": "type9",
          "text": "text9"
        },
        {
          "type": "type4",
          "text": "text4"
        },
        {
          "type": "type6",
          "text": "text6"
        }
      ],
      "images": [
        {
          "src": "http://cvbcvcv",
          "caption": "caption"
        }
      ]
    }]
}

The class that I am using is:

// MainObject.h
@interface MainObject : MTLModel <MTLJSONSerializing>
@property (strong, nonatomic) NSArray *sectionsArray;
+ (NSValueTransformer *)sectionsArrayJSONTransformer;
@end


@interface Section : MTLModel <MTLJSONSerializing>
@property (strong, nonatomic) NSString *title;
@property (assign, nonatomic) NSString *level;
@property (strong, nonatomic) NSArray *content;
@property (strong, nonatomic) NSArray *images;
+ (NSValueTransformer *)contentJSONTransformer;
+ (NSValueTransformer *)imagesJSONTransformer;
@end


@interface Content : MTLModel <MTLJSONSerializing>
@property (strong, nonatomic) NSString *type;
@property (strong, nonatomic) NSString *text;
@end


@interface Image : MTLModel <MTLJSONSerializing>
@property (strong, nonatomic) NSString *src;
@property (strong, nonatomic) NSString *caption;
@end

and

//MainObject.m
@implementation MainObject

+ (NSDictionary *)JSONKeyPathsByPropertyKey
{
    return @{
             @"sectionsArray" : @"sections",};
}

+ (NSValueTransformer *)sectionsArrayJSONTransformer
{
    return [MTLJSONAdapter dictionaryTransformerWithModelClass:[Section class]];
}

@end


@implementation Section

+ (NSDictionary *)JSONKeyPathsByPropertyKey
{
    return @{
             @"title" : @"title",
             @"level" : @"level",
             @"content" : @"content",
             @"images" : @"images",};
}

+ (NSValueTransformer *)contentJSONTransformer
{    
    return [MTLJSONAdapter arrayTransformerWithModelClass:[Content class]];
}

+ (NSValueTransformer *)imagesJSONTransformer
{
    return [MTLJSONAdapter arrayTransformerWithModelClass:[Image class]];
}

@end


@implementation Content

+ (NSDictionary *)JSONKeyPathsByPropertyKey
{
    return @{
             @"type" : @"type",
             @"text" : @"text",};
}

@end


@implementation Image

+ (NSDictionary *)JSONKeyPathsByPropertyKey
{
    return @{
             @"src" : @"src",
             @"caption" : @"caption",};
}

@end

Then, when I make the call to the service and try to parse the json with the following code, being responseObject the data obtained from server, the data appears nil:

for (NSArray *array in [responseObject valueForKey:@"sections"]) {
    NSArray *seccionArray = [MTLJSONAdapter modelsOfClass:[Section class] fromJSONArray:array error:nil];
}

I have tried a lot of ways to parse this data well, but the app always crashes or returns nil. I hope you can help me to solve this

Answer 1

Why can't just one line using NSJSONSerialization ?

NSMutableDictionary *yourArray = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];

Then you fetch what you want from your array...