当应用程序在 macOS 上关闭时在 @EnvironmentObject 上迭代数组

Question

我有一个 @EnvironmentObject 为我的主视图提供一个数组。声明如下：

my_app.swift

@main
struct My_AppApp: App {    
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(DataModel())
        }
    }
}

ContentView.swift

struct NoteItem: Codable, Hashable, Identifiable {
    let id: UUID
    var text: String
    var date = Date()
    var changed: Bool = false
}

final class DataModel: ObservableObject {
    @AppStorage("mytestapp") public var notes: [NoteItem] = []
    init() {
        self.notes = self.notes.sorted(by: {
            [=11=].date.compare(.date) == .orderedDescending
        })
    }    
}

我从ContentView.swift中的不同观点称呼这个为：

struct AllText: View {
   @EnvironmentObject private var data: DataModel
}

我在 my_app.swift 中添加了检测用户何时关闭应用程序的功能，以便我可以执行一些操作。

#if os(macOS)
class AppDelegate: NSObject, NSApplicationDelegate {
    func applicationWillTerminate(_ aNotification: Notification) {        
        // trying to iterate on the struct within DataModel() here
        print("app closing")
    }
}
#endif


@main
struct My_AppApp: App {
    
    #if os(macOS)
        @NSApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
    #endif
    
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(DataModel())
        }
    }
}

现在，我正在尝试访问 DataModel() 中的结构，这样我就可以检查每个元素是否都有更改集，但无论我尝试什么，或者我如何声明 environmentObject，我都会得到 segfault，或 No ObservableObject of type DataModel found. A View.environmentObjectfor DataModel may be missing as an ancestor of this view.

等错误

如何访问该 DataModel 并对其进行迭代，以便在关闭应用程序时执行操作？

谢谢。

Answer 1

这是可能的方法 - 在 ContentView 出现时注入数据模型，例如

#if os(macOS)
class AppDelegate: NSObject, NSApplicationDelegate {

    var dataModel: DataModel?   // << here 

    func applicationWillTerminate(_ aNotification: Notification) {        
        print("app closing")

        // use self.dataModel? here
    }
}
#endif


@main
struct My_AppApp: App {
    
    #if os(macOS)
        @NSApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
    #endif
    
    private let dataModel = DataModel()    // << here !!

    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(self.dataModel)    // << here !!
                .onAppear {
#if os(macOS)
                   appDelegate.dataModel = self.dataModel  // << here !!
#endif
                }
        }
    }
}

当应用程序在 macOS 上关闭时在 @EnvironmentObject 上迭代数组

Iterating an array on an @EnvironmentObject when the application closes on macOS

macos

swiftui

macos-big-sur