NSError *error;
NSData *data = nil;

data = [[NSData dataWithContentsOfFile:@"nieistniejcy_plik" 
                               options:NSDataReadingUncached 
                                 error:&error] retain];

if (data == nil) {
   NSLog(@"Wystpi bd: %@", [error localizedDescription]);
} else {
   NSLog(@"Wszystko w porzdku");
}
