Alphanumeric array sorting

Question

I have a list of alphanumeric names and when I run the code below the digits are ordered before the A-Z (0-9 A-Z).

How can I make this NSSortDescriptor put the digit at the end of the array (A-Z 0-9)?

NSSortDescriptor *sortNameSortDescriptor = 
[NSSortDescriptor sortDescriptorWithKey:@"sortName"
ascending:YES
selector:@selector(localizedStandardCompare:)];

NSArray *sortedArray = [sortSectionsArray sortedArrayUsingDescriptors:@[ sortNameSortDescriptor ]];

Answer 1

Perhaps you could use an NSComparator based sort descriptor?

Rough Outline

NSSortDescriptor *sort = [[NSSortDescriptor alloc] initWithKey:@"sortName" ascending:YES
     comparator:^NSComparisonResult(NSString* obj1, NSString* obj2) 
     {
            //Return negative number, zero or positive based on 
            //first letter being number or alpha. 
            //If obj1 starts with a letter and obj2 starts with a number then
            //return NSOrderedAscending. . . otherwise just return [obj1 comppare:obj2];

            //To test if first chararacter is a letter:

            NSRange first = [obj1 rangeOfComposedCharacterSequenceAtIndex:0];
            NSRange match = [obj1 rangeOfCharacterFromSet:[NSCharacterSet letterCharacterSet] options:0 range:first];
            if (match.location != NSNotFound) {//Implement above comment}
     }];