Question

我尝试在我的应用程序（.sqlite，.sqlite-wal和.sqlite-shm）中预加载我的数据库，但我不能。

我试试这个：

func preloadDBData()
{
    let sqlitePath = Bundle.main.path(forResource: "leksikonPreload", ofType: "sqlite")
    let sqlitePath_shm = Bundle.main.path(forResource: "leksikonPreload", ofType: "sqlite-shm")
    let sqlitePath_wal = Bundle.main.path(forResource: "leksikonPreload", ofType: "sqlite-wal")

    let URL1 = URL(fileURLWithPath: sqlitePath!)
    let URL2 = URL(fileURLWithPath: sqlitePath_shm!)
    let URL3 = URL(fileURLWithPath: sqlitePath_wal!)
    let URL4 = URL(fileURLWithPath: NSPersistentContainer.defaultDirectoryURL().relativePath + "/leksikonPreload.sqlite")
    let URL5 = URL(fileURLWithPath: NSPersistentContainer.defaultDirectoryURL().relativePath + "/leksikonPreload.sqlite-shm")
    let URL6 = URL(fileURLWithPath: NSPersistentContainer.defaultDirectoryURL().relativePath + "/leksikonPreload.sqlite-wal")

    if !FileManager.default.fileExists(atPath: NSPersistentContainer.defaultDirectoryURL().relativePath + "/leksikonPreload.sqlite") {
        // Copy 3 files
        do {
            try FileManager.default.copyItem(at: URL1, to: URL4)
            try FileManager.default.copyItem(at: URL2, to: URL5)
            try FileManager.default.copyItem(at: URL3, to: URL6)

            print("=======================")
            print("FILES COPIED")
            print("=======================")

        } catch {
            print("=======================")
            print("ERROR IN COPY OPERATION")
            print("=======================")
        }
    } else {
        print("=======================")
        print("FILES EXIST")
        print("=======================")
    }
}

并在我的appDelegate didFinishLaunchingWithOptions方法中调用preloadDBData（）。我的核心数据模型的名称：“leksikon”，我的预装数据的名称：“leksikonPreload”。这个函数工作正常并且在“FILES COPYED”和“FILES EXIST”时写入，但是当我尝试打印我的数据时 - 我的数组包含0个元素，但我确信，leksikonPreload包含12个值。我的打印代码：

func printData() {
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let context = appDelegate.persistentContainer.viewContext
    let fetchRequest: NSFetchRequest<Word> = Word.fetchRequest()

    do
    {
        let arr = try context.fetch(fetchRequest)
        for obj in arr {
            print(obj.engValue)
            print(obj.rusValue)
            print(obj.was)
        }
    }
    catch
    {
        print(error.localizedDescription)
    }
}

Answer 1

我遇到了同样的问题。

我有一个预加载的数据库，名为：BenedictusCoreData.sqlite

我将其添加到我的项目中。并修改了AppDelegate：

    lazy var persistentContainer: NSPersistentContainer = {

    let container = NSPersistentContainer(name: "BenedictusCoreData")
    container.loadPersistentStores(completionHandler: { (storeDescription, error) in
        if let error = error as NSError? {

            fatalError("Unresolved error \(error), \(error.userInfo)")
        }
    })
    return container
}()

// MARK: - Preload data from my sqlite file.

func preloadDBData() {

    let sqlitePath = Bundle.main.path(forResource: "BenedictusCoreData", ofType: "sqlite")
    let originURL = URL(fileURLWithPath: sqlitePath!)
    let destinationURL = URL(fileURLWithPath: NSPersistentContainer.defaultDirectoryURL().relativePath + "/BenedictusCoreData.sqlite")

    if !FileManager.default.fileExists(atPath: NSPersistentContainer.defaultDirectoryURL().relativePath + "/BenedictusCoreData.sqlite") {
        // Copy file
        do {
            try FileManager.default.copyItem(at: originURL, to: destinationURL)

            print("=======================")
            print("FILE COPIED")
            print("=======================")

        } catch {
            print("=======================")
            print("ERROR IN COPY OPERATION")
            print("=======================")
        }
    } else {
        print("=======================")
        print("FILE EXIST")
        print("=======================")
    }

}

我只复制了sqlite文件，因为我没有wal和shm文件，因为我只想在首次启动时复制该文件，并且仅用于读取目的。

在AppDelegate didFinishLaunchingWithOptions中调用preloadDBData（）函数。并在首次启动时说“文件已复制”。然后在启动时说“ FILE EXIST”。因此，似乎文件已被复制。

项目中的模型文件称为BenedictusCoreData.xcdatamodeld，项目名称为BenedictusCoreData

在ViewController中，我编写了以下内容：

    var encyclicalsArray = [Encyclicals]()

let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    loadItems()

}

func loadItems() {

    let request: NSFetchRequest<Encyclicals> = Encyclicals.fetchRequest()
    do {
        try encyclicalsArray = context.fetch(request)
        for encyclical in encyclicalsArray {
            print(encyclical.titulo_es!)
            print(encyclical.date!)
            print(encyclical.idURL!)
        }
    } catch {
        print("Error fetching encyclicals: \(error)")
    }

}

它什么也不打印。但是，我的sqlite预加载文件在此表中有三个条目。

使用CoreData，Swift 4

1 个答案: