gistfile1.m

/**
 * Draws a smiley inside the given rectangle. The mood value (0...1) is used
 * to make the smiley happy or sad.
 *
 * @param rect Rectangle to draw the smiley into
 * @param mood Happy (= 1) or sad (= 0) or anything in between
 */
-(void)drawSmileyInRect:(CGRect)rect withMood:(float)mood {
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGContextSaveGState(ctx);
    CGContextTranslateCTM(ctx, rect.origin.x, rect.origin.y);
    CGContextScaleCTM(ctx, rect.size.width/8 ,rect.size.height/8); // Hint: Original Coordinate System has a width an height of 8 pixels
    
    // Eyes:
    CGContextFillEllipseInRect(ctx, CGRectMake(2, 2, 1, 1));
    CGContextFillEllipseInRect(ctx, CGRectMake(5, 2, 1, 1));
    
    // Lips:
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:CGPointMake(1.5, 5.5)];
    [path addQuadCurveToPoint:CGPointMake(6.5, 5.5) controlPoint:CGPointMake(4, 4+mood*4)];
    
    path.lineWidth = 0.5;
    path.lineCapStyle = kCGLineCapRound;
    [[UIColor blackColor] setStroke];
    [path stroke];
 
    CGContextRestoreGState(ctx);
}