Xcode 7 beta 5，Swift 2：UITableViewCell的子视图在运行时未添加到contentView [英] Xcode 7 beta 5, Swift 2: UITableViewCell's subviews are not added to the contentView at runtime

问题描述

使用Xcode 7 beta 5和Swift 2时出现以下现象：

使用在故事板中创建的自定义UICollectionViewCell时，单元格的子视图不会添加到单元格的 contentView 。因此，单元格在运行时保持空白。

但是，如果我为单元格创建自定义单元格类，然后以编程方式将子视图添加到contentView并设置其 frame 显示单元格的内容：

  class Cell：UITableViewCell {
 
 @IBOutlet弱var标签：UILabel！ 
 
覆盖func awakeFromNib（）{
 super.awakeFromNib（）
 
 NSLog（subiews.count =％d，contentView.subviews.count）//打印0
 
 contentView.subviews.count 
 contentView.addSubview（label）
 
 label.frame = CGRect（x：0，y：0，width ：200，身高：21）
} 
} 
  

再次，无需手动添加标签（已在故事板中添加！）并设置其框架，它在运行时将不可见！在故事板中，标签是内容视图的子视图。在运行时它不是。

我在最新的Xcode 6中使用Swift 1.2无法观察到这种行为。

有人可以证实这种愚蠢的行为吗？并且可能提供更简单的解决方法？

编辑：
在添加这些视图后，可以应用对单元格子视图的幸运视图约束以编程方式 contentView 。因此，至少手动设置它们的帧是不必要的。

解决方案

这里有一个类似的问题

Following phenomena happens when using Xcode 7 beta 5 and Swift 2:

When using a custom UICollectionViewCell that is created in the storyboard, the cell's subviews are not added to the cell's contentView. Thus the cell remains blank on runtime.

If I however create a custom cell class for the cell and then programmatically add the subviews to the contentView and set their frame the cell's content is displayed:

class Cell : UITableViewCell {

    @IBOutlet weak var label: UILabel!

    override func awakeFromNib() {
        super.awakeFromNib()

        NSLog("subiews.count=%d", contentView.subviews.count) // prints "0"

        contentView.subviews.count
        contentView.addSubview(label)

        label.frame = CGRect(x: 0, y: 0, width: 200, height: 21)
    }
}

Again, without manually adding the label (that has been added in the storyboard!) and setting its frame, it would not be visible at runtime! In the storyboard the label is a subview of the content view. At run time it is not.

I cannot observe this behavior in latest Xcode 6 with Swift 1.2.

Can somebody confirm this silly behavior? And maybe provide an easier workaround?

Edit: Luckily view constraints on the cell's subviews are applied after these views have been added programmatically to contentView. Thus at least manually setting their frames is not necessary.

解决方案

There is a similar question here UITableView Empty with iOS 9 beta 5 update

And my answer for it https://stackoverflow.com/a/32052154/2674336

I can't say if this is a universal solution, but in the exact same scenario (tablviewcell content empty at runtime after updating to XCode 7 beta 5) this solved it for me:

I had to go through every single item inside the content view (including all constraints) and tick the checkbox "Installed" in the properties inspector. Initially only wR hR was checked.

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