Answer by coverback for How can i save JSON objects to Core Data?

The best way to do that would be to create entities corresponding to JSON structure. Easiest was is when each JSON object becomes an entity, and arrays become arrays of entities. Be reasonable, however, and don't introduce too much overkill for JSON subobjects that are essentially part of its superobject.

When you have created entities, you can start off with the parsing and translation. Use some JSON framework (starting from iOS5 there's one from Apple) and parse JSON string into object tree, where root item is either an NSArray or NSDictionary, and subelements will be NSArray, NSDictionary, NSNumber, NSString or NSNull.

Go over them one by one in iterational loops and assign according values to your core data entity attributes. You can make use of NSKeyValueCoding here and avoid too much manual mapping of the attribute names. If your JSON attributes are of the same name as entity attributes, you'll be able to just go over all dictionary elements and parse them into attributes of the same name.

Example

My parsing code in the similar situation was as follows:

NSDictionary *parsedFeed = /* your way to get a dictionary */;for (NSString *key in parsedFeed) {    id value = [parsedFeed objectForKey:key];    // Don't assign NSNull, it will break assignments to NSString, etc.    if (value && [value isKindOfClass:[NSNull class]])         value = nil;    @try {        [yourCreatedEntity setValue:value forKey:property];    } @catch (NSException *exception) {        // Exception means such attribute is not defined in the class or some other error.    }}

This code will work in trivial situation, however, it may need to be expanded, depending on your needs:

• With some kinds of custom mappings in case you want your JSON value be placed in differently named attribute.
• If your JSON has sub-objects or arrays of sub-objects, you will need to detect those cases, for example in setters, and initiate new parsing one level deeper. Otherwise with my example you will face the situation that assigns NSDictionary object to an NSManagedObject.

I don't think it is reasonable to dive into these, more advanced matters in scope of this answer, as it will expand it too much.