1. 画线（实线与虚线）

UIBezierPath * xPath = [UIBezierPath bezierPath];

[xPath moveToPoint:CGPointMake(YLabelWidth + width * i, height)];//设置初始点的位置

[xPath addLineToPoint:CGPointMake(YLabelWidth + width * i, 0)];

CAShapeLayer * xLayer = [CAShapeLayer layer];

xLayer.strokeColor = _lineDashColor.CGColor;

xLayer.fillColor = [UIColor clearColor].CGColor;

xLayer.lineDashPattern = @[@3,@2];//三个像素的实线，两个像素的空格构成的虚线

xLayer.lineWidth = 1;

xLayer.path = xPath.CGPath;

[self.layer addSublayer:xLayer];

参考文章：*  http://justsee.iteye.com/blog/1972853  UIBezierPath的使用

*  http://www.jianshu.com/p/1d0e405f166e  CGContext的使用