- (void)drawRect:(CGRect)rect
{
    UIBezierPath *blueHalf = [UIBezierPath bezierPath];
    [blueHalf addArcWithCenter:CGPointMake(100, 100) radius:90.0 startAngle:-M_PI_2 endAngle:M_PI_2 clockwise:YES];
    [blueHalf setLineWidth:4.0];
    [[UIColor blueColor] setStroke];
    [blueHalf stroke];

    UIBezierPath *redHalf = [UIBezierPath bezierPath];
    [redHalf addArcWithCenter:CGPointMake(100, 100) radius:90.0 startAngle:M_PI_2 endAngle:-M_PI_2 clockwise:YES];
    [redHalf setLineWidth:4.0];
    [[UIColor redColor] setStroke];
    [redHalf stroke];
}