使用预填充的核心数据部署应用程序

Question

我正在尝试使用已填充的Core Data 发布我的应用程序。我找到了一些链接，他们解释了如何做到这一点，但要么它不起作用，要么答案很旧。我关注了this 的帖子，但它不起作用。一种解决方案可能是将.sqlite 文件导入应用程序文件夹，然后将它们复制到设备的文件系统，但我不知道该怎么做。有什么方法可以使用现有实体和记录预填充我的核心数据？

Answer 1

这是我找到的解决方案：

第 1 步
在另一个应用程序中填充您的Core Data 并使用此代码获取文件的路径：

let paths = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)
let documentsDirectory = paths[0]
print(documentsDirectory)

第二步
将您的 3 个带有 .sqlite 扩展名的文件拖到您的 xCode 项目中。 （请务必选择Add to targets 选项）。

第三步
创建函数来检查应用的首次运行。

func isFirstLaunch() -> Bool {
    let hasBeenLaunchedBeforeFlag = "hasBeenLaunchedBeforeFlag"
    let isFirstLaunch = !UserDefaults.standard.bool(forKey: hasBeenLaunchedBeforeFlag)
    if (isFirstLaunch) {
        UserDefaults.standard.set(true, forKey: hasBeenLaunchedBeforeFlag)
        UserDefaults.standard.synchronize()
    }
    return isFirstLaunch
}

第四步
复制到AppDelegate:

func getDocumentsDirectory()-> URL {
    let paths = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)
    let documentsDirectory = paths[0]
    return documentsDirectory
}

// MARK: - Core Data stack

lazy var persistentContainer: NSPersistentContainer = {
    let container = NSPersistentContainer(name: "ProjectName")

    let appName: String = "ProjectName"
    var persistentStoreDescriptions: NSPersistentStoreDescription

    let storeUrl = self.getDocumentsDirectory().appendingPathComponent("FileName.sqlite")

    if UserDefaults.isFirstLaunch() {
        let seededDataUrl = Bundle.main.url(forResource: "FileName", withExtension: "sqlite")
        try! FileManager.default.copyItem(at: seededDataUrl!, to: storeUrl)
    }

    let description = NSPersistentStoreDescription()
    description.shouldInferMappingModelAutomatically = true
    description.shouldMigrateStoreAutomatically = true
    description.url = storeUrl

    container.persistentStoreDescriptions = [description]

    container.loadPersistentStores(completionHandler: { (storeDescription, error) in
        if let error = error as NSError? {
            fatalError("Unresolved error \(error), \(error.userInfo)")
        }
    })
    return container
}()

第 5 步
如果您想删除新的Core Data 文件，请使用此功能：

func deleteFiles() {
    let fileManager = FileManager.default
    let documentsUrl =  FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask).first! as NSURL
    let documentsPath = documentsUrl.path

    do {
        if let documentPath = documentsPath {
            let fileNames = try fileManager.contentsOfDirectory(atPath: "\(documentPath)")
            print("all files in cache: \(fileNames)")
            for fileName in fileNames {
                if (fileName.contains("YourFileName")) {
                    let filePathName = "\(documentPath)/\(fileName)"
                    try fileManager.removeItem(atPath: filePathName)
                }
            }
            let files = try fileManager.contentsOfDirectory(atPath: "\(documentPath)")
            print("all files in cache after deleting images: \(files)")
        }
    } catch {
        print("Could not clear temp folder: \(error)")
    }
}

Answer 2

我推荐以下教程。它解释了如何做到这一点。

https://www.youtube.com/watch?v=xcV8Ow9nWFo

Answer 3

我的第 4 步版本：

  private func isFirstLaunch() -> Bool {
    let isFirstLaunchKey = "firstLaunch"
    let userDefaults = UserDefaults.standard
    let isFirstLaunch = !userDefaults.bool(forKey: isFirstLaunchKey)
    
    if isFirstLaunch { userDefaults.setValue(true, forKey: isFirstLaunchKey) }
    return isFirstLaunch
  }

  lazy var persistentContainer: NSPersistentContainer = {
    let container = NSPersistentContainer(name: "YourProjectCDName")
    
    if isFirstLaunch() {
      if let storeUrl = container.persistentStoreDescriptions.first?.url,
         let seededDataUrl = Bundle.main.url(forResource: "YourProjectCDName", withExtension: "sqlite") {
        do {
          try container.persistentStoreCoordinator.replacePersistentStore(
            at: storeUrl,
            destinationOptions: nil,
            withPersistentStoreFrom: seededDataUrl,
            sourceOptions: nil,
            ofType: NSSQLiteStoreType)
        } catch {
          print(error.localizedDescription)
        }
      } else {
        fatalError("Cannot unwrap URLs!")
      }
    }
    
    container.loadPersistentStores(completionHandler: { (storeDescription, error) in
      if let error = error as NSError? {
        fatalError("Unresolved error \(error), \(error.userInfo)")
      }
    })
    return container
  }()