Cocos2d，iOS 7.1：CCLabelTTF隐藏了ccDrawLine

Question

I'm trying to use a CCLabelTTF in the upper part of the screen, while drawing a line in the lower part using ccDrawLine. When the app starts, the label is empty, and after a while it's updated with some text. The line is drawn constantly in the draw method like that:

- (void)draw {

    ccDrawColor4B(0, 255, 0, 0);
    glLineWidth(40.0f);
    ccDrawLine(ccp(0, 0), ccp(200, 200)); 
}

Thing is, the second the label is updated with text and actually displays something, the line disappears and is not drawn again, even if the label goes empty again. I'm not using any background at the moment, so it's not hiding it. I tried playing around with zOrders (even though the label and the line are in different areas of the screen) and still the line disappears. I even tried creating a CCSprite subclass with only an init and a draw method, and using it to draw the line. Here's what I have in this class:

@implementation DrawingSprite
- (id)init {
    if (self = [super init]) {

    }
    return self;
}

- (void)draw {

    ccDrawColor4B(0, 255, 0, 0); //Color of the line RGBA
    glLineWidth(40.0f); //Stroke width of the line
    ccDrawLine(ccp(0, 0), ccp(200, 200));
}
@end

And here's what I add to my main layer:

_topLabel = [CCLabelTTF labelWithString:@"" fontName:@"Helvetica" fontSize:24];
_topLabel.position = ccp(winSize.width/2, winSize.height - 100);
_topLabel.color = ccc3(255,255,255);
_topLabel.zOrder = -1;
[self addChild:_topLabel];

_drawingSprite = [DrawingSprite node];
_drawingSprite.zOrder = 10;
[self addChild:_drawingSprite];

What am I missing?

Answer 1

I think you should add

[super draw];

att the begiining of your draw method when you override the draw method of CCSprite. Only then a subclassed CCSprite does “sprite rendering” for its overridden method.