//设置cell圆角
- (void)tableView:(UITableView *)tableView willDisplayCell:(nonnull UITableViewCell *)cell forRowAtIndexPath:(nonnull NSIndexPath *)indexPath {
    
    // 圆角角度
    CGFloat radius = 6.f;
    // 设置cell 背景色为透明
    cell.backgroundColor = UIColor.clearColor;
    // 创建两个layer
    CAShapeLayer *normalLayer = [[CAShapeLayer alloc] init];
    CAShapeLayer *selectLayer = [[CAShapeLayer alloc] init];
    // 获取显示区域大小
    CGRect bounds = CGRectInset(cell.bounds, 6, 0);
    // 获取每组行数
    NSInteger rowNum = [tableView numberOfRowsInSection:indexPath.section];
    // 贝塞尔曲线
    UIBezierPath *bezierPath = nil;
    if (rowNum == 1) {
        bezierPath = [UIBezierPath bezierPathWithRoundedRect:bounds byRoundingCorners:UIRectCornerAllCorners cornerRadii:CGSizeMake(radius, radius)];
    }else{
        if (indexPath.row == 0) {
            // 每组第一行（添加左上和右上的圆角）
            bezierPath = [UIBezierPath bezierPathWithRoundedRect:bounds byRoundingCorners:UIRectCornerTopLeft|UIRectCornerTopRight cornerRadii:CGSizeMake(radius, radius)];
        }else if (indexPath.row == rowNum - 1){
            // 每组最后一行（添加左下和右下的圆角）
            bezierPath = [UIBezierPath bezierPathWithRoundedRect:bounds byRoundingCorners:UIRectCornerBottomLeft|UIRectCornerBottomRight cornerRadii:CGSizeMake(radius, radius)];
        }else{
            // 每组不是首位的行不设置圆角
            bezierPath = [UIBezierPath bezierPathWithRect:bounds];
        }
    }
    // 把已经绘制好的贝塞尔曲线路径赋值给图层，然后图层根据path进行图像渲染render
    normalLayer.path = bezierPath.CGPath;
    selectLayer.path = bezierPath.CGPath;

    UIView *nomarBgView = [[UIView alloc] initWithFrame:bounds];
    // 设置填充颜色
   
    normalLayer.fillColor = [[UIColor whiteColor] CGColor];
    // 添加图层到nomarBgView中
    [nomarBgView.layer insertSublayer:normalLayer atIndex:0];
    nomarBgView.backgroundColor = UIColor.clearColor;
    //         nomarBgView.backgroundColor = UIColor.whiteColor;
    cell.backgroundView = nomarBgView;
    //此时圆角显示就完成了，但是如果没有取消cell的点击效果，还是会出现一个灰色的长方形的形状，再用上面创建的selectLayer给cell添加一个selectedBackgroundView
    UIView *selectBgView = [[UIView alloc] initWithFrame:bounds];
    selectLayer.fillColor = [[UIColor whiteColor] CGColor];
    [selectBgView.layer insertSublayer:selectLayer atIndex:0];
    selectBgView.backgroundColor = UIColor.clearColor;
    cell.selectedBackgroundView = selectBgView;

    if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {
        [cell setLayoutMargins:UIEdgeInsetsZero];
    }
    if ([cell respondsToSelector:@selector(setSeparatorInset:)]){
        [cell setSeparatorInset:UIEdgeInsetsZero];
    }
}