Question

My JSON has the following structure:

{
"<Person>k__BackingField" =     {
    "_email" = "[e-mail]";
    "_emailUpdate" = 1;
    "_firstName" = "First";
    "_lastName" = "Last";
};
"<SharedKey>k__BackingField" = "some-long-random-string";
}

I’m using restkit to login as this person. It creates the Post, and gets that response correctly. My mappings are set up like this:

+(void)ConfigureAPI
{
[super ConfigureAPI];
// Initialize RestKit
[RKObjectManager managerWithBaseURLString: @"www.api_root.com/";
Class<RKParser> parser = [[RKParserRegistry sharedRegistry] parserClassForMIMEType:@"application/json"];
[[RKParserRegistry sharedRegistry] setParserClass:parser forMIMEType:@"text/plain"];

RKObjectMapping *mapping;

// Person
mapping = [RKObjectMapping mappingForClass:[Person class]];
[mapping mapKeyPath:@"_email" toAttribute:@"email"];
[mapping mapKeyPath:@"_emailUpdate" toAttribute:@"emailUpdate"];
[mapping mapKeyPath:@"_firstName" toAttribute:@"firstName"];
[mapping mapKeyPath:@"_lastName" toAttribute:@"lastName"];
[[RKObjectManager sharedManager].mappingProvider setMapping:mapping forKeyPath:@"<Person>k__BackingField"];
}

When I run the application and call the function that gets the JSON response, I get the following error:

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<__NSCFString 0x7b41800> valueForUndefinedKey:]: this class is not key value coding-compliant for the key <Person>k__BackingField.'

Anybody know why I’m getting this? everything seems to be set up correctly

EDIT

In case it helps, this is how I’m handling the response:

    // when you get the response...
    request.onDidLoadResponse = ^(RKResponse *response){
        RKObjectMapper *mapper = [RKObjectMapper mapperWithObject:[response bodyAsString] mappingProvider:[RKObjectManager sharedManager].mappingProvider];

        Person *person = nil;
        RKObjectMappingResult *mappingResult = [mapper performMapping];
        person = [mappingResult asObject];
    };

Answer 1

You are not converting the response string into a JSON object before passing it to the RKObjectMapper. You were passing in the string value of the response which does not respond to valueForKey: which explains the exception you were getting. You can easily convert it into an object like this:

request.onDidLoadResponse = ^(RKResponse *response){

    NSError *error;
    id jsonObject = [response parsedBody:&error];

    if(error)
        NSLog(@"Error parsing JSON: %@", error.localizedDescription);
    else {
        RKObjectMapper *mapper = [RKObjectMapper mapperWithObject:jsonObject mappingProvider:[RKObjectManager sharedManager].mappingProvider];

        Person *person = nil;
        RKObjectMappingResult *mappingResult = [mapper performMapping];
        person = [mappingResult asObject];
    }
};