I have subclassed UIImageView and tried to override drawRect so I could draw on top of the image using Quartz 2D. I know this is a dumb newbie question, but I'm not seeing what I did wrong. Here's the interface:

#import <UIKit/UIKit.h>

@interface UIImageViewCustom : UIImageView {

}
- (void)drawRect:(CGRect)rect;

And the implementation:

#import "UIImageViewCustom.h"

@implementation UIImageViewCustom

- (id)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
    }
    return self;
}

- (void)drawRect:(CGRect)rect {
    // do stuff
}

I set a breakpoint on drawRect and it never hits, leading me to think it never gets called at all. Isn't it supposed to be called when the view first loads? Have I incorrectly overridden it?