tableView 对section整体切圆角和加阴影

参考文章：https://zhuanlan.zhihu.com/p/269559400

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {

// 圆角角度

CGFloat radius = 10.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, 10, 0);

// cell的backgroundView

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

// 获取每组行数

NSInteger rowNum = [tableView numberOfRowsInSection:indexPath.section];

// 贝塞尔曲线

UIBezierPath *bezierPath = nil;

if (rowNum == 1) {

// 一组只有一行（四个角全部为圆角）

bezierPath = [UIBezierPath bezierPathWithRoundedRect:bounds byRoundingCorners:UIRectCornerAllCorners cornerRadii:CGSizeMake(radius, radius)];

normalBgView.clipsToBounds = NO;

} else {

normalBgView.clipsToBounds = YES;

if (indexPath.row == 0) {

normalBgView.frame = UIEdgeInsetsInsetRect(bounds, UIEdgeInsetsMake(-5, 0, 0, 0));

CGRect rect = UIEdgeInsetsInsetRect(bounds, UIEdgeInsetsMake(5, 0, 0, 0));

// 每组第一行（添加左上和右上的圆角）

bezierPath = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:(UIRectCornerTopLeft|UIRectCornerTopRight) cornerRadii:CGSizeMake(radius, radius)];

} else if (indexPath.row == rowNum - 1) {

normalBgView.frame = UIEdgeInsetsInsetRect(bounds, UIEdgeInsetsMake(0, 0, -5, 0));

CGRect rect = UIEdgeInsetsInsetRect(bounds, UIEdgeInsetsMake(0, 0, 5, 0));

// 每组最后一行（添加左下和右下的圆角）

bezierPath = [UIBezierPath bezierPathWithRoundedRect:rect 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];

}

// 阴影

normalLayer.shadowColor = [UIColor blackColor].CGColor;

normalLayer.shadowOpacity = 0.3;

normalLayer.shadowOffset = CGSizeMake(0, 0);

normalLayer.path = bezierPath.CGPath;

normalLayer.shadowPath = bezierPath.CGPath;

// 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;

// 设置填充颜色

normalLayer.fillColor = [UIColor whiteColor].CGColor;

// 添加图层到nomarBgView中

[normalBgView.layer insertSublayer:normalLayer atIndex:0];

normalBgView.backgroundColor = UIColor.clearColor;

cell.backgroundView = normalBgView;

// 替换cell点击效果

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

selectLayer.fillColor = [UIColor colorWithWhite:0.95 alpha:1.0].CGColor;

[selectBgView.layer insertSublayer:selectLayer atIndex:0];

selectBgView.backgroundColor = UIColor.clearColor;

cell.selectedBackgroundView = selectBgView;

}

备注（去了这里没发现区别，iOS 14 上，其它未验证）