使用自动布局约束动态尺寸表视图细胞 [英] Dynamically size Table View Cells using Auto Layout constraints
问题描述
我已经完全后,我的最新调查结果修订的问题。
I have revised the question completely after my latest findings.
我的目标是实现以下效果:
My goal is to implement the following effect:
- 有一个简单的表格视图
- 的用户选择行
- 选定行展开,露出下面的原始另一个标签
请注意,我知道,这可以通过插入/删除选择以下任一单元格来实现,我已经有成功实施使用该方法。
Please note that I am aware, that this can be achieved by inserting/deleting cells below the selected one, I already have a successful implementation using that method.
这一次,我要尝试实现这一目标使用自动布局约束。
This time, I want to try to achieve this using Auto Layout constraints.
我有一个可用的示例项目的人来检查,也的opened问题。总之,这里是我到目前为止已经试过:
I have a sample project available for anyone to check, and also opened an issue. To summarize, here's what I've tried so far:
我有以下几点看法如下行为:
I have the following views as actors here:
- 单元格的内容视图
- 顶视图,包含主标签(主视图)
- 仰视图,主视图下方,包含最初是隐藏标签(详细信息视图)
我已经设置了自动布局限制我的牢房内的下列方式(请注意,这是严格伪语言):
I have set up Auto Layout constraints within my cell the following way (please note that this is strictly pseudo-language):
- mainView.top = contentView.top
- mainView.leading = contentView.leading
- mainView.trailing = contentView.trailing
- mainView.bottom = detailView.top
- detailView.leading = contentView.leading
- detailView.trailing = contentView.trailing
- detailView.bottom = contentView.bottom
- detailView.height = 0
我有一个自定义的的UITableViewCell
子类中,有多个网点,但在这里最重要的是对高度约束的插座提到previously:这里的想法是设置其恒
0默认,但被选中单元格时,将其设置为44,那么它将变得可见:
I have a custom UITableViewCell
subclass, with multiple outlets, but the most important here is an outlet for the height constraint mentioned previously: the idea here is to set its constant
to 0 by default, but when the cell is selected, set it to 44, so it becomes visible:
override func setSelected(selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
detailViewHeightConstraint.constant = selected ? detailViewDefaultHeight : 0
UIView.animateWithDuration(0.3) {
self.layoutIfNeeded()
}
}
我有以下结果:
所以效果是工作,但不正是我最初的想象。相反,主推的观点了,我想细胞的高度为增长时,将显示详细视图,和缩了回来时,它的隐藏。
So the effect is working, but not exactly how I originally imagined. Instead of pushing the main view up, I want the cell's height to grow when the detail view is shown, and shrink back when it's hidden.
我已经在运行时检查我的布局层次:
I have examined my layout hierarchy during runtime:
- 的初始状态是确定。内容视图的高度等于我主视图的高度(在此情况下,它的125点)。
- 当选择小区,则细节视图的高度约束增加至44点和两个视图被正确层叠vertically.But代替单元格的内容视图延伸,而是,主视图收缩。立>
我需要的是以下几点:表格视图单元格的内容视图的高度应等于
What I need is the following: the height of table view cell's content view should be equal to
- 主视图的高度,当详细视图的身高限制是0(目前这个工程)
- 主视图高度+时,详细视图的高度约束已正确设置详细视图高度(这不起作用)。
我如何必须设置我的约束来实现这一目标?
How do I have to set my constraints to achieve that?
推荐答案
After a significant amount of research, I think I've found the solution with the help of this great article.
下面是使细胞大小调整所需的步骤:
Here are the steps needed to make the cell resize:
在Main和详细视图,我原本设定为水平,垂直居中的标签。这是不够的,自我上浆细胞。我需要的第一件事是使用垂直间隔的限制,而不是简单的校准设置我的布局:
Within the Main, and Detail Views, I have originally set the labels to be horizontally and vertically centered. This isn't enough for self sizing cells. The first thing I needed is to set up my layout using vertical spacing constraints instead of simple alignment:
此外,你应该设置在主箱的垂直COM pression阻力为1000。
Additionally you should set the Main Container's vertical compression resistance to 1000.
详细视图更是一个有点棘手:除了建立适当的垂直约束,你也有自己的优先级发挥,达到预期的效果:
The detail view is a bit more tricky: Apart from creating the appropriate vertical constraints, you also have to play with their priorities to reach the desired effect:
- 的明细集装箱的高度约束为44分,而是使之选,(根据文档,任何比要求,下将被视为这样的),设置其优先级为999。
- 在明细集装箱,建立垂直间隔的限制,并给他们的998当务之急。
主要思路如下:
- 默认情况下,该电池已展开。为了实现这一目标,我们必须编程设置明细集装箱的高度约束的常数0。由于其优先级高于单元格内容视图中的垂直限制较高,后者将被忽略,所以明细集装箱将被隐藏。
- 当我们选择单元格,我们希望它扩大。这意味着,垂直约束必须掌握控制权:我们设置优先级明细集装箱的高度约束的东西很低(我用的250),所以它有利于内容视图中的制约因素被忽略
我不得不修改我的的UITableViewCell
子类来支持这些操作:
I had to modify my UITableViewCell
subclass to support these operations:
// `showDetails` is exposed to control, whether the cell should be expanded
var showsDetails = false {
didSet {
detailViewHeightConstraint.priority = showsDetails ? lowLayoutPriority : highLayoutPriority
}
}
override func awakeFromNib() {
super.awakeFromNib()
detailViewHeightConstraint.constant = 0
}
要触发的行为,我们必须重写的tableView(_:didSelectRowAtIndexPath方法:)
:
To trigger the behavior, we must override tableView(_:didSelectRowAtIndexPath:)
:
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
tableView.deselectRowAtIndexPath(indexPath, animated: false)
switch expandedIndexPath {
case .Some(_) where expandedIndexPath == indexPath:
expandedIndexPath = nil
case .Some(let expandedIndex) where expandedIndex != indexPath:
expandedIndexPath = nil
self.tableView(tableView, didSelectRowAtIndexPath: indexPath)
default:
expandedIndexPath = indexPath
}
}
请注意,我已经介绍了 expandedIndexPath
来跟踪我们目前扩大指数:
Notice that I've introduced expandedIndexPath
to keep track of our currently expanded index:
var expandedIndexPath: NSIndexPath? {
didSet {
switch expandedIndexPath {
case .Some(let index):
tableView.reloadRowsAtIndexPaths([index], withRowAnimation: UITableViewRowAnimation.Automatic)
case .None:
tableView.reloadRowsAtIndexPaths([oldValue!], withRowAnimation: UITableViewRowAnimation.Automatic)
}
}
}
设置属性将导致表视图重装了合适的索引,给我们一个完美的机会来告诉细胞,它是否应该扩大:
Setting the property will result in the table view reloading the appropriate indexes, giving us a perfect opportunity to tell the cell, if it should expand:
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier(cellIdentifier, forIndexPath: indexPath) as! ExpandableTableViewCell
cell.mainTitle = viewModel.mainTitleForRow(indexPath.row)
cell.detailTitle = viewModel.detailTitleForRow(indexPath.row)
switch expandedIndexPath {
case .Some(let expandedIndexPath) where expandedIndexPath == indexPath:
cell.showsDetails = true
default:
cell.showsDetails = false
}
return cell
}
最后一步是使自身在大小 viewDidLoad中()
:
override func viewDidLoad() {
super.viewDidLoad()
tableView.contentInset.top = statusbarHeight
tableView.rowHeight = UITableViewAutomaticDimension
tableView.estimatedRowHeight = 125
}
下面是结果:
细胞现在可以正确地调整大小自己。您可能会注意到动画还是有点不可思议,但是,这并不属于这一问题的范围固定。
Cells now correctly size themselves. You may notice that the animation is still a bit weird, but fixing that does not fall into the scope of this question.
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