Question

I need to deserialize JSON string to custom complex objects.

For example lets say I have the json string:

{"Menu": {
"categoryList": {
"Category": [
{"name": "Cat1"},
{"name": "Cat1"},
{"name": "Cat3"}
]
}
}}

How can I deserialize this string to initialize a Menu object that has a categoryList which includes 3 category objects of type Category class? Is there any way to to this?

Answer 1

Try using a JSON parser.

http://code.google.com/p/json-framework/

It will analyse your string and give you back an NSObject (NSArray or NSDictionary) that represents your data.

EDIT:

Well, as the OP wanted to get a custom object instead of an NSDictionary/NSArray, it could be implemented something as the following (assuming that the dificulty would get the correct data and set each of the new object properties)

Based on the code provided by @andrewsardone, one could easily implement a function using KVO to get a new object with the properties set accordingly, after handling the JSON parsing with whatever solution fits your project better

+(id) objectFromDictionary:(NSDictionary *)dict {

    id entry = [[self alloc] init];

    Class aClass = [entry class];

    do {

        unsigned int outCount, i;
        objc_property_t *properties = class_copyPropertyList(aClass, &outCount);
        for (i = 0; i < outCount; i++) {
            objc_property_t property = properties[i];
            NSString *propertyName = [[[NSString alloc] initWithCString:property_getName(property) encoding:NSUTF8StringEncoding] autorelease];
            id propertyValue = [dict objectForKey:propertyName];
            if (propertyValue && ![propertyValue isEqual:[NSNull null]]) {
                [entry setValue:propertyValue forKey:propertyName];
            }
        } 

        free(properties);

        //added to take care of the class inheritance
        aClass = [aClass superclass];

    } while (![[[aClass class] description] isEqualToString:[NSObject description]]);

    return [entry autorelease];
}