//一定要重写UIView类中的-(void)drawRect:(CGRect)rect方法才能画线；
//绘制UIView
-(void)drawRect:(CGRect)rect
{
[self drawLine];
}
/**
* 画线
*/
-(void)drawLine
{
//1.获取上下文
CGContextRef context = UIGraphicsGetCurrentContext();
//2.创建可变的路径并设置路径
CGMutablePathRef path = CGPathCreateMutable();
//1）设置起始点
CGPathMoveToPoint(path, NULL, 65, 215);
//2）设置目标点
CGPathAddLineToPoint(path, NULL, 115, 220);
//3.将路径添加到上下文
CGContextAddPath(context, path);
//4.设置上下文属性
/**
kCGPathStroke: 画线 (空心）
kCGPathFill: 填充 (实心)
kCGPathFillStroke: 即画线又填充
*/
CGContextDrawPath(context, kCGPathFillStroke);
//5.绘制路径
CGContextDrawPath(context, kCGPathFillStroke);
//6.释放 路径
CGPathRelease(path);
}