AutoLayout 视图使应用程序在 popViewController 上崩溃

If instead of setting my received image to them I set an empty one ([[UIImage alloc] init] or UIImage()) in Swift as is my case exactly) it doesn't crash anymore.

我什至尝试从应用程序包中设置一个虚拟图像，但这也会导致它崩溃.

I even tried setting a dummy image from the app bundle but that makes it crash too.

任何建议将不胜感激！

更新 1

再次查看代码，我还发现有一个与那些 UIImageViews 相关的约束，这也会使崩溃在消除时消失.这是一个纵横比约束，看起来像这样

Looking trough the code once more I also found out that there is a constraint related to those UIImageViews that also makes the crash to go away when eliminated. It's an aspect ratio constraint and it looks like this

imageView.addConstraint(NSLayoutConstraint(item: imageView, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: imageView, attribute: NSLayoutAttribute.Height, multiplier: 8.0 / 5.0, constant: 0.0))

我做错了吗?我真的需要满足这个纵横比，所以我不能真正删除它

Am I doing something wrong? I really need this aspect ratio to be satisfied so I can't really remove it

更新 2

再搞砸一点，我想出了一个让它工作的方法.但我对它不满意，因为它没有让我明白发生了什么，而且它有点像 hack

Messing a little bit more with it I've figured a way to make it work. But I'm not happy with it 'cause it didn't made me understand what's going on and it's kind of a hack

让我给你布置我的视图结构:

Let me layout my view structure to you:

• 查看
  • 滚动视图
    • 内容视图
      • 封面 ImageView(来自 IB)
      • 标题标签(来自 IB)
      • ...更多标签或 ImageViews 在代码中的随机顺序...

      这些视图的放置方式是这样的:

      The way these views are placed is like this:

      • Cover ImageView 与 ContentView 一样宽，纵横比为 8:5，顶部没有空间
      • 每个标签都有一个10px的前导空格和一个10px的尾随空格
      • 每个 ImageView 与 ContentView 一样宽，纵横比为 8:5
      • 所有视图之间都有 10px 的间隙，最后一个与 ContentView
      的底部间距为 10px
      • The Cover ImageView is as wide as the ContentView and has an aspect ratio of 8:5 with no space on top
      • Each Label has a 10px leading space and a 10px trailing space
      • Each ImageView is as wide as the ContentView and has an aspect ratio of 8:5
      • All views have a 10px gap beewtwen them and the last one has 10px bottom spacing to the ContentView

      我对崩溃的解决方法是从 viewWillDisappear 上的堆栈中删除 ContentView，但这会使 ViewController 弹出时屏幕闪烁.

      My fix to my crash was to remove ContentView from the stack on viewWillDisappear but that makes the screen flash when the ViewController is popped.

      我已经检查了我的约束创建代码 1000 次，这似乎是正确的.如果你想看，请告诉我，我会在这里发布

      I've checked my constraints creating code a 1000 times and it seems right. If you want to see it let me know and I'll post it over here

      推荐答案

      把这个放在这里，以防有人遇到与动态代码生成的 aspectRatio 约束相同的问题.我在纵横比约束中切换了 Height 和 Width 关系的顺序(与问题中的比较):

      Just putting this here in case anyone has the same issue with a dynamic, code-generated aspectRatio constraint. I switched the order of the Height and Width relationship in the aspect-ratio constraint (compare to the one in the question):

      aspectConstraint = NSLayoutConstraint(item: cardMedia, attribute: NSLayoutAttribute.Height , relatedBy: NSLayoutRelation.Equal, toItem: cardMedia, attribute: NSLayoutAttribute.Width, multiplier: aspect, constant: 0.0)
      

      其中乘数aspect的计算公式为:

      Where the multiplier aspect is calculated by:

      let aspect = image.size.height / image.size.width
      

      这似乎阻止了崩溃的发生.希望这对某人有所帮助.

      And that seems to stop the crash from happening. Hope this helps someone.

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