swift 在图片上根据点数组划线。

func drawLineInImageWithImage(imageView:UIImageView,points:[CGPoint]){
        UIGraphicsBeginImageContext(imageView.frame.size);
        imageView.image?.drawInRect(CGRectMake(0, 0, imageView.frame.size.width, imageView.frame.size.height));
        CGContextSetLineCap(UIGraphicsGetCurrentContext(), CGLineCap.Round);
        CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
     CGContextSetAllowsAntialiasing(UIGraphicsGetCurrentContext(), true);
        CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), self.lineColor.r(),self.lineColor.g(),self.lineColor.b(),self.lineColor.a());
        CGContextBeginPath(UIGraphicsGetCurrentContext());
        let begin = points[0];
        CGContextMoveToPoint(UIGraphicsGetCurrentContext(), begin.x,begin.y);//起点坐标
        for point in points{
            CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), point.x, point.y);
        }
        //终点坐标
        CGContextStrokePath(UIGraphicsGetCurrentContext());
    imageView.image=UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    }