Sorting NSString values as if NSInteger using NSSortDescriptor

You can do this by implementing a custom comparator block when creating your NSSortDescriptor:

NSSortDescriptor *aSortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"sort" ascending:YES comparator:^(id obj1, id obj2) {

    if ([obj1 integerValue] > [obj2 integerValue]) {
        return (NSComparisonResult)NSOrderedDescending;
    }
    if ([obj1 integerValue] < [obj2 integerValue]) {
        return (NSComparisonResult)NSOrderedAscending;
    }
    return (NSComparisonResult)NSOrderedSame;
}];
self.myList = [NSMutableArray arrayWithArray:[unsortedList sortedArrayUsingDescriptors:[NSArray arrayWithObject:aSortDescriptor]]];

See Apple documentation here