Adjusting size of rect before Quartz drawing to avoid jaggy round-rect and circle strokes

drawing.m

- (void)drawRect:(CGRect)rect
{
    // line weight 
    CGFloat strokeWidth = 2.0f
    
    // adjust size of the canvas to get rid of nasty jaggies
    rect.size.width -= strokeWidth;
    rect.size.height -= strokeWidth;
    rect.origin.x += strokeWidth / 2.0;
    rect.origin.y += strokeWidth / 2.0;
    
    // set up drawing
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetAllowsAntialiasing(context, YES);
    CGContextSetShouldAntialias(context, YES);
    CGContextSetStrokeColorWithColor(context, [UIColor blackColor].CGColor);
    CGContextSetLineWidth(context, strokeWidth);
    CGContextSetFillColorWithColor(context, [UIColor blueColor].CGColor);
    
    // draw the fill
    CGContextFillEllipseInRect(context, rect);
    CGContextStrokeEllipseInRect(context, rect);
}