Question

I use several NSComparators in my iOS app which compare objects by NSString or NSNumber properties. This is fairly easy because NSString has caseInsensitiveCompare: and NSNumber has compare:. How do I compare bools or ints though? For booleans, code could get pretty tangled quite quickly, as my comparision functions take a (bool)ascending parameter. I’ve noticed Objective C often has obscure global functions for this type of thing.

Currently I’m using this code to compare booleans:

NSComparator comp = ^(id id1, id id2) {
    ListItem *comp1 = nil, 
             *comp2 = nil;
    if([id1 isKindOfClass:[ListItem class]]){
        if(ascending){
            comp1 = (ListItem*)id1;
            comp2 = (ListItem*)id2;
        }else{
            comp1 = (ListItem*)id2;
            comp2 = (ListItem*)id1;
        }
    } 
    if(h1!=nil && h2!=nil){
        if((h1.isInBasket && h2.isInBasket) || (!h1.isInBasket && !h2.isInBasket)){
            return 0;
        } else if(h1.isInBasket && !h2.isInBasket) {
            return 1;
        } else {
            return -1;
        }
    } else {
        return 0;
    }

}

Answer 1

Bools (BOOL, Boolean) and integers (int, long, unsigned, etc.) are just plain C integral types and you compare them with the standard C comparison operators <, >, == etc. Same holds for char (also an integral type), float, etc. and the named variants such as NSInteger.