I'm trying to use objective-c blocks for some iPhone programming and am getting the following link time error:

The relevant code is:

- (NSDictionary *) getDistances {

 CLLocationCoordinate2D parkingSpace;
 NSMutableDictionary *dict;
 NSIndexSet *indexForUser;


 BOOL (^test)(id obj, NSUInteger idx, BOOL *stop);

 test = ^ (id obj, NSUInteger idx, BOOL *stop) {

  NSString *user = (NSString *)[(NSDictionary *)obj valueForKey:@"userid"];

  if ([user isEqualToString:self->sharedUser.userName]) {
    return YES;
  }
  return NO;
 };


 [self->sharedUser.availableParking indexesOfObjectsPassingTest:test];
}

Any help would be very much appreciated!!