RestKit - Load data from local json file

RestKit Local Loading

NSString *filePath = [[NSBundle mainBundle] pathForResource:JohnSmith ofType:@"json"];
NSData *data = [NSData dataWithContentsOfFile:filePath];
if (data) {
  NSString *jsonString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
  KCUser *appUser = [[KCUser alloc] init];
  
  NSString* MIMEType = @"application/json";
  NSError* error;
  NSData *data = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
  id parsedData = [RKMIMETypeSerialization objectFromData:data MIMEType:MIMEType error:&error];
  if (parsedData == nil && error) {
    NSLog(@"parser error");
  }
    
  NSDictionary *mappingsDictionary = @{ @"appUser": [KCUser mapping] };
  RKMapperOperation *mapper = [[RKMapperOperation alloc] initWithRepresentation:parsedData mappingsDictionary:mappingsDictionary];
  mapper.targetObject = appUser;
  NSError *mappingError = nil;
  BOOL isMapped = [mapper execute:&mappingError];
  if (isMapped && !mappingError) {
    [[KCUserSingleton sharedKCUserSingleton] setUser:appUser];
  }
  else {
    NSLog(@"error desc: %@", error.localizedDescription);
    NSLog(@"error reason: %@", error.localizedFailureReason);
    NSLog(@"error suggestion: %@", error.localizedRecoverySuggestion);
  }
}

What is the targetObject for?

thanks for the snippet!