Unable to add a category to a CPArrayController (cappuccino)

I'm trying to add a method to the CPArrayController class via a category. The template for adding reverse to the CPString works fine but I'm unable to add anything to the CPArrayController. While compiling I get the error

SyntaxError: * Could not find definition for class "CPArrayController"

Here is my code:

@impo开发者_Go百科rt <AppKit/CPArrayController.j>

    @implementation CPArrayController (Inserting)

    - (CPObject)insertAndReturn
    {
        if (![self canInsert]) return nil;
        var newObject = [self automaticallyPreparesContent] ? [self newObject] : [self _defaultNewObject];
        [self addObject:newObject];
        return newObject;
    }
    @end

Any idea why ?

CPArrayController ist Part of AppKit.

So you need to import it, like :

@import <AppKit/CPArrayController.j>

@implementation CPArrayController (Inserting)

- (CPObject)insertAndReturn
{
    if (![self canInsert]) return nil;
    var newObject = [self automaticallyPreparesContent] ? [self newObject] : [self _defaultNewObject];
    [self addObject:newObject];
    return newObject;
}
@end