- (void)drawRect:(CGRect)rect

{

    CGContextRef ctx = UIGraphicsGetCurrentContext();

    //一、 画线

    // 1.先创建一个路径

    CGMutablePathRef linePath = CGPathCreateMutable();

    // 2.拼接路径

    CGPathMoveToPoint(linePath, nil, , );

    CGPathAddLineToPoint(linePath, nil, , );

    // 添加路径到上下文

    CGContextAddPath(ctx, linePath);

    //二、 画圆

    CGMutablePathRef circlePath = CGPathCreateMutable();

    CGPathAddEllipseInRect(circlePath, nil, CGRectMake(, , , ));

    CGContextAddPath(ctx, circlePath);

    // 渲染

    CGContextStrokePath(ctx);

　　// Creat\Copy\retain 用过之后都要做一次release

     CGPathRelease(linePath);

     CGPathRelease(circlePath);

}