如何使用swift 3 xcode 8在核心数据中预加载数据库 [英] How to pre load database in core data using swift 3 xcode 8

问题描述

我有一个包含数据的数据库，我想在应用程序中预加载它。在swift 3之前它可以工作，我已经按照本教程： http：// www .appcoda.com / core-data-preload-sqlite-database / 但如何为swift 3加载相同的数据库？由于引入了 NSPersistentContainer ，如何加载项目中的.sqlite文件？

I have a database with data and I want to preload that in application. Before swift 3 it works and I have followed this tutorial : http://www.appcoda.com/core-data-preload-sqlite-database/ But how to load same database for swift 3? As NSPersistentContainer is introduced how can I load .sqlite file which is in my project?

推荐答案

实际上，在swift 3中更改了创建数据库的默认路径。所以现在代码看起来像：

Actually the default path where database was created is changed in swift 3 . So now the code will look like :

func preloadDBData() {
    let sqlitePath = Bundle.main.path(forResource: "MyDB", ofType: "sqlite")
    let sqlitePath_shm = Bundle.main.path(forResource: "MyDB", ofType: "sqlite-shm")
    let sqlitePath_wal = Bundle.main.path(forResource: "MyDB", 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 + "/MyDB.sqlite")
    let URL5 = URL(fileURLWithPath: NSPersistentContainer.defaultDirectoryURL().relativePath + "/MyDB.sqlite-shm")
    let URL6 = URL(fileURLWithPath: NSPersistentContainer.defaultDirectoryURL().relativePath + "/MyDB.sqlite-wal")

    if !FileManager.default.fileExists(atPath: NSPersistentContainer.defaultDirectoryURL().relativePath + "/MyDB.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("=======================")
    }
}

现在你可以从AppDelegate的 didFinishLaunchWithOptions 方法调用这个方法，这将预装数据库我们已经申请了。

Now you can call this method from AppDelegate's didFinishLaunchWithOptions method and this will preload database which we have put in application.

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