Extra line drawn when drawing an arc with Core Graphics

Question

I'm currently having a problem with custom drawing with core graphics. When I try to draw a kind of rectangle with a rounded border, i get an extra line that i don't want. I've read the documentation and it says that when you draw an arc it draw a line to the origin of the arc. But i don't succeed in finding a solution that would avoid this line. Here is a pic :

So i want to avoid this grey line at the top, under my arc

And here is my code :

//Tracer
    CGContextBeginPath(context);
    CGContextSetStrokeColorWithColor(context, wormBorderColor);
    CGContextSetFillColorWithColor(context, wormFillColor);

    //Tracer la ligne de gauche
    CGContextMoveToPoint(context, leftX, startingY);
    CGContextAddLineToPoint(context, leftX, startingY-wormHeight);
    //CGContextClosePath(context);

    //tracer l'arc supérieur
    CGContextMoveToPoint(context, rightX, startingY-wormHeight);
    CGContextAddArc(context, centerX, startingY-wormHeight, echelleSize/2, 0,M_PI , 1);
    CGContextClosePath(context);

    CGContextAddLineToPoint(context, rightX, startingY);



    //CGContextAddRect(context, CGRectMake(leftX, startingY, rightX-leftX, wormHeight));
    //CGContextClosePath(context);


    CGContextStrokePath(context);

Please excuse my poor english.

Answer 1

The horizontal line at the bottom of the arc is caused by the CGContextClosePath. To make this same image without the horizontal line change the code:

//tracer l'arc supérieur
CGContextMoveToPoint(context, rightX, startingY-wormHeight);
CGContextAddArc(context, centerX, startingY-wormHeight, echelleSize/2, 0,M_PI , 1);
CGContextClosePath(context);

CGContextAddLineToPoint(context, rightX, startingY);

to:

//tracer l'arc supérieur
CGContextMoveToPoint(context, rightX, startingY-wormHeight);
CGContextAddArc(context, centerX, startingY-wormHeight, echelleSize/2, 0,M_PI , 1);


CGContextMoveToPoint(context, rightX, startingY-wormHeight);
CGContextAddLineToPoint(context, rightX, startingY);

Edit:

Modified the code to draw the path in a way that it can be filled, and added a fill at the end.

//Tracer
CGContextBeginPath(context);
CGContextSetStrokeColorWithColor(context, wormBorderColor);
CGContextSetFillColorWithColor(context, wormFillColor);

//Déplacez à l'origine
CGContextMoveToPoint(context, leftX, startingY);

//Tracer la ligne de gauche
CGContextAddLineToPoint(context, leftX, startingY-wormHeight);

//tracer l'arc supérieur - clockwise
CGContextAddArc(context, centerX, startingY-wormHeight, echelleSize/2, 0,M_PI , 0);

//Tracer la ligne de droite
CGContextAddLineToPoint(context, rightX, startingY);

CGContextStrokePath(context);
CGContextFillPath(context);

Sorry for my poor French ;-)