NSArray NSMutableArray sortUsingSelector example objc

The code is collected from  http://www.cocoabuilder.com/archive/cocoa/44099-void-sortusingselector-sel-comparator.html

This article explains how to use sortUsingSelector and what parameter it takes.

> Hello;
> I am new to apple and ObjectiveC and started by playing around with
> NSArray and NSMutableArray to learn something about the native
> datatypes.
>
> The question I have How do I sort a NSArray using
> - (void)sortUsingSelector:(SEL)comparator
>
> What does (SEL)comparator mean??

It means that comparator is a method (or a message).

It should be a method like this one:

- (NSComparisonResult) comparator:(ClassInTheArray *) inObject

You can either write your own for your type of Object or use a Category
like for this one:

@interface NSString (InsensitiveSearch)

- (NSComparisonResult)compareInsensitive:(NSString *)aString;

@end

@implementation NSString(InsensitiveSearch)

- (NSComparisonResult)compareInsensitive:(NSString *)aString
{
    return [self compare:aString options:NSCaseInsensitiveSearch];
}

@end

Sorting the array will be then done with this code:

[myArray sortUsingSelector:@selector(compareInsensitive:)];