Looking for info on custom drawing of interface components (Cocoa)

+ (Class) cellClass
{
    return [OurButtonCell class];
}

- (void)drawRect:(NSRect)rect
{
    // first get the cell to draw inside our bounds
    // then draw a focus ring if that's appropriate
}

- (void)drawInteriorWithFrame: (NSRect) rect inView: (NSView *) controlView
{
    // a bunch of drawing code
}