Question

All,

I would like to sort this mutable dictionary of arrays keys like so: A-Z 0-9 but it’s coming back sorted 0-9 A-Z. How can I sort it such that the alpha chars come before the numbers? Perhaps there is a built-in method that does this or should I create a category that extends NSString?

    NSArray *sKeysArray = [[listContent allKeys] sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)];
    NSString *sectionKey = [sKeysArray objectAtIndex:section];
    NSArray *sectionValues = [listContent valueForKey:sectionKey];

Answer 1

Sadly there’s no method in NSString that will directly do this. Instead of writing a category, I would just use NSArrays sortedArrayUsingComparator: method:

NSArray *sKeysArray = [[listContent ALlKeys] sortedArrayUsingComparator:^(id obj1, id obj2) {
// Code to compare obj1 and obj2 and return an NSComparisonResult here; return NSOrderedAscending if obj1 should come before obj2 
}];

To do each comparison, I would use NSString‘s – enumerateSubstringsInRange:options:usingBlock: passing NSStringEnumerationByComposedCharacterSequences for options (basically enumerating characters, except that unicode characters sequences which are actually one “letter” are combined). And when you’re comparing two characters, use something like the answer to this question to detect when obj1 is a number and obj2 is regular letter and return NSOrderedDescending, otherwise just use regular compare:.