CocoaDev

I want to sort an array of NSString either alphabetically, or sorted by length… Yet, the NSSortDescriptors are confusing me… There’s probably a single line of code that can solve my problem, but I can’t figure…

- (void)sortUsingSelector:(SEL)comparator In this method, how do I refer to the first and second object to be compared ?

– Trax

The selector will be sent to one of your objects, with the other object as the parameter. For example: (Rewritten for more clarity)

@implementation FooHolder

• (void)compareTo:(FooHolder *)other { if([self foo] < [other foo]) return NSOrderedAscending; else if([self foo] > [other foo]) return NSOrderedDescending; else return NSOrderedSame; } @end

In the example above, where does the variable “foo” come from? Check out the rewritten version.

To answer the original question: foo is an instance variable in the class that -compareTo: is in.

This may help: http://theocacao.com/document.page/87/

It’s a simple category that allows you to create inline arrays of sort descriptors. You can then use those descriptors on an array by calling -sortedArrayUsingDescriptors:. - ScottStevenson