drawLayer not called when subclassing CALayer - cocoa

Question

I have a simple CALayer subclass (BoxLayer) with this drawLayer method:
- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx {
NSLog(#"drawLayer");
NSGraphicsContext *nsGraphicsContext;
nsGraphicsContext = [NSGraphicsContext graphicsContextWithGraphicsPort:ctx
flipped:NO];
[NSGraphicsContext saveGraphicsState];
[NSGraphicsContext setCurrentContext:nsGraphicsContext];
// ...Draw content using NS APIs...
NSPoint origin = { 21,21 };
NSRect rect;
rect.origin = origin;
rect.size.width = 128;
rect.size.height = 128;
NSBezierPath * path;
path = [NSBezierPath bezierPathWithRect:rect];
[path setLineWidth:4];
[[NSColor whiteColor] set];
[path fill];
[[NSColor grayColor] set];
[path stroke];
[NSGraphicsContext restoreGraphicsState];
}
I then have this awakeFromNib in my NSView subclass:
- (void)awakeFromNib {
CALayer* rootLayer = [CALayer layer];
[self setLayer:rootLayer];
[self setWantsLayer:YES];
box1 = [CALayer layer];
box1.bounds = CGRectMake(0, 0, 70, 30);
box1.position = CGPointMake(80, 80);
box1.cornerRadius = 10;
box1.borderColor = CGColorCreateGenericRGB(255, 0, 0, 1);
box1.borderWidth = 1.5;
[rootLayer addSublayer:box1];
box2 = [BoxLayer layer];
[box2 setDelegate:box2];
[box2 setNeedsDisplay];
[rootLayer addSublayer:box2];
}
My drawLayer is never called though, but why not?
Thank you

Answer 1

Possibly because the frame of your layer seems to be equal to CGRectZero, so the OS might think it's invisible so it doesn't need to draw it.
On a side note, why are going the complicated way of setting the layer's delegate to itself and implementing drawLayer:inContext: instead of using drawInContext: directly?