创建新应用时，如何停止CoreData产生样板代码？

问题描述

新开发者问题

在Xcode中，当创建一个包含CoreData的新应用程序时，它会生成样板代码，该代码来自我从在线教程课程中下载的基本“提醒”应用程序。如何使Xcode恢复为默认配置？

我创建了6个具有不同配置的应用程序，并且仅在包含CoreData时才生成。 我包括了UI预览的屏幕截图。模拟器为空。

这是 ContentView.swift

中的代码

import SwiftUI
import CoreData

struct ContentView: View {
    @Environment(\.managedobjectContext) private var viewContext

    @FetchRequest(
        sortDescriptors: [NSSortDescriptor(keyPath: \Item.timestamp,ascending: true)],animation: .default)
    private var items: FetchedResults<Item>

    var body: some View {
        List {
            ForEach(items) { item in
                Text("Item at \(item.timestamp!,formatter: itemFormatter)")
            }
            .onDelete(perform: deleteItems)
        }
        .toolbar {
            #if os(iOS)
            EditButton()
            #endif

            Button(action: addItem) {
                Label("Add Item",systemImage: "plus")
            }
        }
    }

    private func addItem() {
        withAnimation {
            let newItem = Item(context: viewContext)
            newItem.timestamp = Date()

            do {
                try viewContext.save()
            } catch {
                // Replace this implementation with code to handle the error appropriately.
                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application,although it may be useful during development.
                let nsError = error as NSError
                fatalError("Unresolved error \(nsError),\(nsError.userInfo)")
            }
        }
    }

    private func deleteItems(offsets: IndexSet) {
        withAnimation {
            offsets.map { items[$0] }.forEach(viewContext.delete)

            do {
                try viewContext.save()
            } catch {
                // Replace this implementation with code to handle the error appropriately.
                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application,\(nsError.userInfo)")
            }
        }
    }
}

private let itemFormatter: DateFormatter = {
    let formatter = DateFormatter()
    formatter.dateStyle = .short
    formatter.timeStyle = .medium
    return formatter
}()

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView().environment(\.managedobjectContext,PersistenceController.preview.container.viewContext)
    }
}

解决方法

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