NSDictionary *userInfo = [error userInfo];
NSString *message;

if (userInfo && [userInfo objectForKey:NSUnderlyingErrorKey]) {
   NSError *underlyingError = [userInfo objectForKey:NSUnderlyingErrorKey];
   message = [underlyingError localizedDescription];
} else {
   message = [error localizedDescription];
}
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Błąd"
                                                message:message
                                               delegate:nil 
                                      cancelButtonTitle:nil  
                                     otherButtonTitles:@"OK", nil];
[alert show];
[alert release];
