tableview 的圆角样式实现demo

 if ([cell respondsToSelector:@selector(tintColor)]) {


        if (tableView==self.tableView) {


         CGFloat cornerRadius = 15.f;


            cell.backgroundColor = UIColor.clearColor;



            // 创建一个shapeLayer


            CAShapeLayer *layer = [[CAShapeLayer alloc] init];


            // 创建一个可变的图像Path句柄，该路径用于保存绘图信息


            CGMutablePathRef pathRef = CGPathCreateMutable();


            // 获取cell的size


            CGRect bounds = CGRectInset(cell.bounds, 0, 0);


            // 这里要判断分组列表中的第一行，每组section的第一行，每组section的中间行


            BOOL addLine = NO;


            // CGPathAddRoundedRect(pathRef, nil, bounds, cornerRadius, cornerRadius);


            if (indexPath.row == 0) {


                // 初始起点为cell的左下角坐标


                CGPathMoveToPoint(pathRef, nil, CGRectGetMinX(bounds), CGRectGetMaxY(bounds));


                // 起始坐标为左下角，设为p1，（CGRectGetMinX(bounds), CGRectGetMinY(bounds)）为左上角的点，设为p1(x1,y1)，(CGRectGetMidX(bounds), CGRectGetMinY(bounds))为顶部中点的点，设为p2(x2,y2)。然后连接p1和p2为一条直线l1，连接初始点p到p1成一条直线l，则在两条直线相交处绘制弧度为r的圆角。


               CGPathAddArcToPoint(pathRef, nil, CGRectGetMinX(bounds), CGRectGetMinY(bounds), CGRectGetMidX(bounds), CGRectGetMinY(bounds), cornerRadius);


                CGPathAddArcToPoint(pathRef, nil, CGRectGetMaxX(bounds), CGRectGetMinY(bounds), CGRectGetMaxX(bounds), CGRectGetMidY(bounds), cornerRadius);



                CGPathAddLineToPoint(pathRef, nil, CGRectGetMaxX(bounds), CGRectGetMaxY(bounds));


                addLine = YES;


            }else if (indexPath.row == [tableView numberOfRowsInSection:indexPath.section]-1) {


                // 初始起点为cell的左上角坐标


                CGPathMoveToPoint(pathRef, nil, CGRectGetMinX(bounds), CGRectGetMinY(bounds));


                CGPathAddArcToPoint(pathRef, nil, CGRectGetMinX(bounds), CGRectGetMaxY(bounds), CGRectGetMidX(bounds), CGRectGetMaxY(bounds), cornerRadius);


                CGPathAddArcToPoint(pathRef, nil, CGRectGetMaxX(bounds), CGRectGetMaxY(bounds), CGRectGetMaxX(bounds), CGRectGetMidY(bounds), cornerRadius);




                CGPathAddLineToPoint(pathRef, nil, CGRectGetMaxX(bounds), CGRectGetMinY(bounds));


            } else {


                // 添加cell的rectangle信息到path中（不包括圆角）


                CGPathAddRect(pathRef, nil, bounds);


                addLine = YES;


            }


            // 把已经绘制好的可变图像路径赋值给图层，然后图层根据这图像path进行图像渲染render


            layer.path = pathRef;


            // 注意：但凡通过Quartz2D中带有creat/copy/retain方法创建出来的值都必须要释放


            CFRelease(pathRef);


            // 按照shape layer的path填充颜色，类似于渲染render


            layer.fillColor = [UIColor redColor].CGColor;




            // 添加分隔线图层


            if (addLine == YES) {


                CALayer *lineLayer = [[CALayer alloc] init];


                CGFloat lineHeight = (1.f / [UIScreen mainScreen].scale);


                lineLayer.frame = CGRectMake(CGRectGetMinX(bounds), bounds.size.height-lineHeight, bounds.size.width, lineHeight);


                // 分隔线颜色取自于原来tableview的分隔线颜色


                lineLayer.backgroundColor = tableView.separatorColor.CGColor;

[layer addSublayer:lineLayer];


            }




            // view大小与cell一致


            UIView *roundView = [[UIView alloc] initWithFrame:bounds];


            // 添加自定义圆角后的图层到roundView中

[roundView.layer insertSublayer:layer atIndex:0];


            roundView.backgroundColor = UIColor.clearColor;




            //cell的背景view


            //cell.selectedBackgroundView = roundView;


            cell.backgroundView = roundView;