ios - 即使不再显示，SwiftUI View 也会不断更新

Question

我有一个简单的 View ，它通过@ObservedObject 属性观察一个对象。像这样:

struct BrowserView: View {
    @ObservedObject var fs: FileStore

    var body: some View {
        List(fs.files) { file in
            NavigationLink(destination: BrowserView(fs: self.fs) {
                FileRow(item: file)
            }
        }
        .onAppear(perform: loadFiles)
    }

    private func loadFiles() {
        fs.loadFiles()
    }
}

所以发生的事情是，当点击一行时，我导航到下一个 View ，它仍然是使用相同数据集的相同浏览器 View (在实际代码中，它还传递其他值，因为它就像一个文件浏览器和当前路径获取也作为参数传递，但为了示例，它实际上不相关)。

问题是，当下一个 BrowserView 出现时，数据集发生变化，这些变化会触发前一个 View 的更新，该 View 不再可见，尝试更新其 UITableView 实际上会使应用程序崩溃。

有什么方法可以告诉 View 在 onDisappear 或类似的东西中禁用它的绑定(bind)吗？如果不是，当只有一个模型(存储)在不同 View 之间共享时，正确的模式是什么？

更新

这是当新 View 被插入堆栈并且新数据已被检索时发生的崩溃日志:

Thread 1 Queue : com.apple.main-thread (serial)
#0  0x00000001b9a4643c in AG::Graph::import_attribute(AG::Subgraph*, AG::Graph&, AG::attribute_t, AGTypeID, AG::ClosureFunctionVV<void>, AG::ClosureFunctionFV<void, AG::ClosureFunctionVV<void> >) ()
#1  0x00000001b9a4c76c in AGGraphImportAttribute ()
#2  0x00000001c52b8280 in ViewGraph.import<A>(_:as:from:) ()
#3  0x00000001c53a9a20 in static StyleType.makeViewList<A>(view:style:inputs:) ()
#4  0x00000001c53a9200 in static ResolvedList._makeViewList(view:inputs:) ()
#5  0x00000001c5203544 in closure #2 in static ModifiedContent<>._makeViewList(view:inputs:) ()
#6  0x00000001c51e723c in specialized static MultiViewModifier._makeViewList(modifier:inputs:body:) ()
#7  0x00000001c51e8274 in protocol witness for static ViewModifier._makeViewList(modifier:inputs:body:) in conformance ButtonActionModifier ()
#8  0x00000001c52020d8 in static ModifiedContent<>._makeViewList(view:inputs:) ()
#9  0x00000001c5203544 in closure #2 in static ModifiedContent<>._makeViewList(view:inputs:) ()
#10 0x00000001c51e81dc in static ViewModifier<>._makeViewList(modifier:inputs:body:) ()
#11 0x00000001c52020d8 in static ModifiedContent<>._makeViewList(view:inputs:) ()
#12 0x00000001c51795c0 in static View.makeViewList(view:inputs:) ()
#13 0x00000001c516b42c in static View._makeViewList(view:inputs:) ()
#14 0x00000001c542524c in AnyViewStorage.makeViewList(view:inputs:) ()
#15 0x00000001c54268a8 in closure #1 in AnyViewList.update(context:) ()
#16 0x00000001c5426648 in AnyViewList.update(context:) ()
#17 0x00000001c54289a0 in partial apply for protocol witness for static UntypedAttribute._update(_:graph:attribute:) in conformance AnyViewList ()
#18 0x00000001b9a3b88c in AG::Graph::UpdateStack::update() ()
#19 0x00000001b9a3bd48 in AG::Graph::update_attribute(unsigned int, bool) ()
#20 0x00000001b9a40cb0 in AG::Subgraph::update(unsigned int) ()
#21 0x00000001c52be0f4 in ViewGraph.runTransaction(in:) ()
#22 0x00000001c52bdea8 in closure #1 in ViewGraph.flushTransactions() ()
#23 0x00000001c52bdb20 in ViewGraph.flushTransactions() ()
#24 0x00000001c52bdc98 in closure #1 in closure #1 in ViewGraph.asyncTransaction<A>(_:mutation:style:) ()
#25 0x00000001c55759c0 in ViewRendererHost.updateViewGraph<A>(body:) ()
#26 0x00000001c52bdc60 in closure #1 in ViewGraph.asyncTransaction<A>(_:mutation:style:) ()
#27 0x00000001c52d9a30 in thunk for @escaping @callee_guaranteed () -> () ()
#28 0x00000001c514ff64 in static NSRunLoop.flushObservers() ()
#29 0x00000001c514fed4 in closure #1 in static NSRunLoop.addObserver(_:) ()
#30 0x00000001c5150004 in @objc closure #1 in static NSRunLoop.addObserver(_:) ()
#31 0x000000018d7acee8 in __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ ()
#32 0x000000018d7a7b78 in __CFRunLoopDoObservers ()
#33 0x000000018d7a8018 in __CFRunLoopRun ()
#34 0x000000018d7a78f4 in CFRunLoopRunSpecific ()
#35 0x0000000197bbe604 in GSEventRunModal ()
#36 0x000000019197b358 in UIApplicationMain ()

Answer 1

你所描述的不应该导致崩溃......试试这个代码:

class Model: ObservableObject {
    @Published var files: [String] = ["red", "black", "blue", "yellow", "orange"]
}

struct ContentView: View {
    var body: some View {
        NavigationView {
            MainView(fs: Model())
        }
    }
}
struct MainView: View {
    @ObservedObject var fs: Model
    
    var body: some View {
        VStack {
            List(fs.files, id: \.self) {  file in
                NavigationLink(destination: MainView(fs: self.fs)) {
                    Text(file)
                }
            }.onAppear {
                self.fs.files.append("New Value")
            }
        }
    }
}

它正在观察模型并在 onAppear 中更新，并反复推送相同的 View 只会更新下一个屏幕和第一个屏幕中的列表。