分组uitableview与阴影

问题描述

任何想法如何在分组的uitableview的边框周围显示阴影（围绕顶部，底部，侧面以及部分圆角的所有边框）。

Any ideas how to show a shadow around the grouped uitableview's border?(around all border at top, bottom, sides as well as around rounded corners of sections).

我需要与图片上完全相同的效果：

I need exactly the same effect like here on the picture:

注意边框附近的小阴影（灰色一，蓝色是背景）

Pay attention to small shadow near the border(gray one, blue is the background)

推荐答案

我想出了一个相当hackish的解决方案，在我看来，所以我不完全满意，但反正！因此，在区段中的一组单元格周围绘制阴影的基本功能是由此实现的。因此我子类化UITableView并实现了layoutSubviews方法，如下：

i came up with a rather "hackish" solution to this in my opinion, so i'm not totally happy with it but anyway! the basic functionality of drawing a drop shadow around a group of cells in a section is acomplished by that. therefore i subclassed UITableView and implemented the layoutSubviews method like this:

- (void) layoutSubviews {
    [super layoutSubviews];

    const CGFloat PageCellBackgroundRadius = 6.0;

    for(int i = 0; i < [self numberOfSections]; i++) {
        NSInteger viewTag = i + 123456;
        CGRect frameRect = [self shadowFrameForSection: i];

        UIView* shadowBackgroundView = [self viewWithTag: viewTag];
        if (shadowBackgroundView) {
            if (!CGRectEqualToRect(frameRect, shadowBackgroundView.frame)) {
                shadowBackgroundView.frame = frameRect;
                CGPathRef shadowPath = [UIBezierPath bezierPathWithRoundedRect: shadowBackgroundView.bounds
                                                             byRoundingCorners: UIRectCornerAllCorners
                                                                   cornerRadii: CGSizeMake(PageCellBackgroundRadius, PageCellBackgroundRadius)].CGPath;
                shadowBackgroundView.layer.shadowPath = shadowPath;
            }

            [self sendSubviewToBack: shadowBackgroundView];
        } else {
            shadowBackgroundView = [[[UIView alloc] initWithFrame: frameRect] autorelease];
            shadowBackgroundView.tag = viewTag;
            shadowBackgroundView.opaque = YES;
            shadowBackgroundView.backgroundColor = [UIColor clearColor];

            shadowBackgroundView.layer.shadowOpacity = 0.3;
            shadowBackgroundView.layer.shadowRadius = 2;
            shadowBackgroundView.layer.shadowColor = [[UIColor blackColor] CGColor];
            shadowBackgroundView.layer.shadowOffset = CGSizeMake(0.0, 1.0);
            CGPathRef shadowPath = [UIBezierPath bezierPathWithRoundedRect: shadowBackgroundView.bounds
                                                         byRoundingCorners: UIRectCornerAllCorners
                                                               cornerRadii: CGSizeMake(PageCellBackgroundRadius, PageCellBackgroundRadius)].CGPath;
            shadowBackgroundView.layer.shadowPath = shadowPath;
            shadowBackgroundView.layer.shouldRasterize = YES;

            [self addSubview: shadowBackgroundView];
        }
    }
}

- (CGRect) shadowFrameForSection: (NSInteger) section {
    CGRect sectionFrame = [self rectForSection: section];

    CGFloat sectionHeaderHeight = CGRectGetHeight([self rectForHeaderInSection: section]);
    CGFloat sectionFooterHeight = CGRectGetHeight([self rectForFooterInSection: section]);

    UIEdgeInsets contentInsets = UIEdgeInsetsMake(sectionHeaderHeight + 1, 10, sectionFooterHeight + 1, 10);
    return UIEdgeInsetsInsetRect(sectionFrame, contentInsets);
}

代码是不言自明的！
基本上是围绕着将UIViews添加到UITableView作为子视图，计算框架的节，然后绘制阴影到添加的UIView的图层。 UITableView提供
一些框架计算的方法：rectForSection等。

the code is self-explanatory i think!basically it revolves around adding UIViews to the UITableView as subviews, for a calculated frame of a section, and then drawing the drop shadow to the layer of the added UIView. UITableView providessome methods for the frame calculations: "rectForSection" etc.

我不满意，因为它觉得不正确添加视图layoutSubviews方法！ （这可以做somwhere else =>表视图委托？）
我也喜欢更多的工作与CALayers，但你不能标记他们！因为我的代码工作的
收缩/扩展已经添加uiviews性能的原因。

i'm not happy with it because it feels not right adding views in the layoutSubviews method! (this could be done somwhere else => table view delegate?)i also would have liked more to work with CALayers, but you can't tag them! because my code works byshrinking/expanding already added uiviews for performance reasons.

在这种形式，解决方案将不工作，如果部分消失或部分是reorderd等
它也表现不好，如果你以动画的方式添加行到表视图等
，但它对静态分组表视图非常有用我认为！

in this form, the solution won't work if sections disappear or if sections are reorderd etc.it also behaves not well if you're adding rows in a animated fashion to the table view etc.but it's quite useful for "static" grouped table views i think!

我也没有测试性能影响，所以使用自己的风险！

i also haven't tested for performance implications, so use at own risk!

所以也许这是一个很好的开始点一个可能更好的解决方案！ ： - ）

so maybe this is a good starting point for a possibly better solution to this! :-)

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