由于没有EnvironmentObject的弹出窗口，SwiftUI Mac OS崩溃 [英] SwiftUI Mac OS crash due to popover without EnvironmentObject

问题描述

我在视图中使用的是PopOver.在这种情况下，我正在对CoreData执行FetchRequest.一切正常.它已连接到我的 Environment(\.managedObjectContext).但是，总是当我调用弹出窗口并重新加载该视图时，它就会崩溃.

I am using a PopOver in my view. In that view I am doing a FetchRequest to CoreData. It is working fine. It is connected to my Environment(\.managedObjectContext). However, always when I call my popover and reload that view, it is crashing.

我读了另一个堆栈溢出"问题，我必须手动将对象推到该弹出窗口.我正在尝试，但仍然崩溃.我正在用它来调用我的弹出窗口:

I read in another Stack Overflow question, that I have to manually push my objects to that popover. I am trying it and it still crashes. I am using this to call my popover:

Button(action:
{
  //Call the PopOver
  self.s_showPopover = true
})
{
  Image("Link")
}
 .padding(.trailing, 16)
 .buttonStyle(PlainButtonStyle())
 .popover(isPresented: self.$s_showPopover, content: { PersonFormPopover().environment(\.managedObjectContext, NSManagedObjectContext.current).environmentObject(userData) })

我可以正确发送对象吗?仅当我至少一次单击弹出窗口时，才会出现崩溃.如果我不单击它，它不会崩溃.

Am I sending my objects correctly? The crash only appear when I click the popover one time minimum. If I don't click it, it doesn't crashes.

在我的PopOver视图中，我什至没有使用该对象，也没有向CoreData发出任何请求.为什么它仍然崩溃?当我重新加载该视图时，它在解析 FetchRequest 时向我显示 foreach 中的错误.看来他那时什么都没有得到.

In my PopOver view I am not even using that Object, or make any request to CoreData. Why is it still crashing? When I reload that view, it shows me the error in my foreach when parsing the FetchRequest. It looks like that he do not get any objects at all then.

这是我的PersonPopOver视图，它只是一个空视图.

This is my PersonPopOver view, it is just an empty view.

struct PersonFormPopover: View {    
    var body: some View {
        Text(/"Hello, World!")
    }
}

struct PersonFormPopover_Previews: PreviewProvider {
    static var previews: some View {
        PersonFormPopover()
    }
}

在弹出窗口之后再次加载视图时，出现以下崩溃消息.

I get following crash message when loading my view again after the popup.

Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)

推荐答案

因此，我终于找到了解决方案.感谢@Asperi的帮助...

So, I finally found a solution. Thanks for the help of @Asperi ...

我在实际视图之前使用的是NavigationView.看来SwiftUI没有将我的 Environment Object 推送到 DetailView .虽然不确定它是否是一个错误，但是可以通过 NavigationLink 和 PopOver 手动将其修复.

I was using a NavigationView before my actual view. It looks like SwiftUI is not pushing my Environment Object to the DetailView. Not sure if it a bug though, however pushing it manually at the NavigationLink and PopOver fixed it.

在遇到相同问题时，这可能对其他人有所帮助.

Maybe it is helpful for other, when struggling with the same issue.

我刚刚将 NavigationLink 更改为以下代码:

I just changed my NavigationLink to the following code:

 NavigationLink(destination: VenueView().environment(\.managedObjectContext, NSManagedObjectContext.current), tag: 4, selection: self.$userData.currentView) {

我正在手动添加环境，它可以正常工作.

There I am adding the environment manually and it works.

我的弹出窗口代码如下:

My code for the popover looked like this:

.popover(isPresented: self.$s_showPopover, content: { PersonFormPopover().environment(\.managedObjectContext, self.managedObjectContext).environmentObject(self.userData)

按照Asperi的建议，我为我的ManagedObjectContext使用了一个本地变量.

I used a local var for my managedObjectContext as Asperi suggested.

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