带关系的核心数据的JSON

Question

根据Ray Wenderlich的新教程,我能够获取JSON数据并将其存储到Core数据中.我很难理解如何使用Core Data中的关系来做到这一点.

这是我的数据模型:

这是我的JSON:

{
    "results": [
        {
        "name": "Trivia 1",
        "objectId": "1000",
        "createdAt": "2012-08-31 18:02:52.249 +0000",
        "updatedAt": "2012-08-31 18:02:52.249 +0000",
        "questions": [
            {
                "text": "Question 1"
            },
            {
                "text": "Question 2"
            },
            {
                "text": "Question 3"
            }
         ]
       }
     ]
}

最后,我在这里设置了managedObject的值:

    //Sets values for ManagedObject, also checks type
    - (void)setValue:(id)value forKey:(NSString *)key forManagedObject:(NSManagedObject *)managedObject {

        NSLog(@"TYPE: %@", [value class]);

        //If managedObject key is "createdAt" or "updatedAt" format the date string to an nsdate
        if ([key isEqualToString:@"createdAt"] || [key isEqualToString:@"updatedAt"]) {
            NSDate *date = [self dateUsingStringFromAPI:value];
            //Set date object to managedObject
            [managedObject setValue:date forKey:key];
        } else if ([value isKindOfClass:[NSArray class]]) {  //<---This would be the array for the Relationship
            //TODO: If it's a Dictionary/Array add logic here
            for(NSDictionary *dict in value){
                NSLog(@"QUESTION");
            }
        } else {
            //Set managedObject's key to string
            [managedObject setValue:value forKey:key];
        }
    }

我已经看过这个问题,但我真的很困惑如何从Ray Wenderlich示例中将各个部分连接在一起.任何帮助将不胜感激.

Answer 1

在你的for循环中你将要做一些特殊的handeling,如果你正在处理一个QuestionGroup,你会知道该对象上的数组是问题(假设它是唯一的数组),所以你可以为每个创建一个新的Question对象.在词典中输入.这将破坏同步引擎的通用性,但如果需要,您可以通过一些额外的步骤重新获得它.

else if ([value isKindOfClass:[NSArray class]]) {
    if ([[managedObject entity] name] isEqualToString:@"QuestionGroup") {
        NSSet *questions = [NSMutableSet set];
        for (NSDictionary *question in value) {
            // create your question object/record
            NSManagedObject *questionManagedObject = [NSEntityDescription insertNewObjectForEntityForName:@"Question" inManagedObjectContext:managedObjectContext];
            // setup your question object
            questionManagedObject.text = [question valueForKey:@"text"];
            // store all the created question objects in a set
            [questions addObject:questionManagedObject];
        }
        // assign the set of questions to the relationship on QuestionGroup
        [managedObject setValue:questions forKey:@"questions"];
    }
}