NSSet *set = [NSSet setWithObjects:@"a", @"b", @"kot",
   @"c", @"mysz", @"ox", @"d", nil];

NSSet *longStrings = 
   [set objectsPassingTest:
      ^BOOL (id obj, BOOL *stop) {
         return [obj length] > 1;
      }];
[longStrings enumerateObjectsUsingBlock:
   ^(id obj, BOOL *stop) {
      NSLog(@"ciąg tekstowy: %@", obj);
   }];
