在 Documents 文件夹中创建一个空白的 Core Data sqlite 文件

Question

当您使用 Xcode 使用 Core Data 创建新项目时，它会创建以下文件：

//
// Persistence.swift

import CoreData

struct PersistenceController {
    static let shared = PersistenceController()

    static var preview: PersistenceController = {
        let result = PersistenceController(inMemory: true)
        let viewContext = result.container.viewContext
        for _ in 0..<10 {
            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)")
        }
        return result
    }()

    let container: NSPersistentContainer

    init(inMemory: Bool = false) {
        container = NSPersistentContainer(name: "aaaaa")
        if inMemory {
            container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null")
        }
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                // 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.

                /*
                 Typical reasons for an error here include:
                 * The parent directory does not exist, cannot be created, or disallows writing.
                 * The persistent store is not accessible, due to permissions or data protection when the device is locked.
                 * The device is out of space.
                 * The store could not be migrated to the current model version.
                 Check the error message to determine what the actual problem was.
                 */
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        })
        container.viewContext.automaticallyMergesChangesFromParent = true
    }
}

这会在应用程序的

sqlite

目录中创建一个空的

Application Support

文件并将其分配给持久性控制器。

如何执行相同的操作，但要在应用程序的

Documents

目录中创建文件并将其分配给持久性控制器，以便我可以开始填充它？

Answer 1

您可以像 inMemory 为 true 时一样设置

NSPersistentStoreDescription

的 url 属性

一个例子

if inMemory {
    container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null")
} else {
    let url = URL.documentsDirectory.appending(path: "aaaaa", directoryHint: .notDirectory)
    container.persistentStoreDescriptions.first!.url = url
}