Swift，以编程方式更改UICollectionViewCell和UILabel（在单元格内）的宽度 [英] Swift, Change width of UICollectionViewCell and UILabel(inside the cell) programmatically

问题描述

我已将单元格的宽度（UICollectionViewCell）设置为等于UICollectionView的宽度，并且我尝试使用该单元格中包含的UILabel执行完全相同的操作。我认为下面的代码正好解释了我想要实现的目标。所以我在这里阅读了一些问题以及一些教程，但我仍然不确定如何实现这一点。

I've set the width of a cell(UICollectionViewCell) to be equal to the width of the UICollectionView and I'm trying to do exactly the same thing with the UILabel that is included inside that cell. I think the code below explains exactly what I'm trying to achieve. So i've read some question here in SO and also a couple of tutorials but I'm still not sure how I can achieve this.

在几个问题中它关于使用 collectionViewLayout 的说法，但我真的在如何在我的代码中使用它。有任何想法吗？谢谢！

In a couple of questions it was saying about using collectionViewLayout but I'm really struggling on how to use it within my code. Any ideas? Thank you!

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    var cell = collectionView.dequeueReusableCellWithReuseIdentifier("myCell", forIndexPath: indexPath) as LocationViewCell
    cell.locationLabel.text = "Hello there!"

    // Set cell & label width to 100%
    let collectionViewWidth = self.collectionView.bounds.size.width
    cell.frame.size.width = collectionViewWidth // Works
    cell.locationLabel.frame.size.width = collectionViewWidth // Does NOT 

更新1

所以我添加了以下内容：

Update 1

So I added the following:

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
    // Set cell width to 100%
    let collectionViewWidth = self.collectionView.bounds.size.width
    return CGSize(width: collectionViewWidth, height: 35)
}

当加载视图时，UILabel的宽度仍然很小。如果我去另一个视图，然后返回，那么它是100％。所以我必须在 viewDidLoad（）中做点什么吧？我已经在使用 self.collectionView.reloadData（）但我猜这只是针对数据。

What happens is that when the view is loaded the UILabel's width is still small. If I go to another view and then return back then it's 100%. So I have to do something in the viewDidLoad() right? I'm already using self.collectionView.reloadData() but I guess that's only for data.

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    var cell = collectionView.dequeueReusableCellWithReuseIdentifier("locationCell", forIndexPath: indexPath) as LocationViewCell
    cell.locationLabel.text = "Hello UILabel"

    // Set cell width to 100%
    let collectionViewWidth = self.collectionView.bounds.size.width
    cell.frame.size.width = collectionViewWidth
    cell.locationLabel.frame.size.width = collectionViewWidth

    return cell
}

推荐答案

它不起作用，因为在调用此方法时，集合视图已经知道单元格应该有多大，因为它已从流委托方法获取它：

It doesn't work because by the time this method is called, the collection view already knows how big the cell should be because it has got it from the flow delegate method:

optional func collectionView(_ collectionView: UICollectionView,
                  layout collectionViewLayout: UICollectionViewLayout,
             sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize

这是你应该设置单元格大小的地方。

This is where you should be setting the size of your cells.

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