使用 Xcode 将预加载的 sqlite db 添加到 iOS 应用程序后找不到表

Question

我有一个预加载的 SQLite 数据库，名为“myDB.dms”。我想打包数据库并从应用程序中访问内容。

首先，我将数据库文件拖放到我的 Xcode ProjectNavigator 窗口中，并在提示符下单击“如果需要复制文件”。

我使用 FMDB 库来访问 SQLite DB。

我创建了一个新的数据库接口类并添加了 3 个不同的方法：

1. openDB
2. 复制数据库
3. 执行查询

因为打包 DB 文件时会在 Bundle 资源文件夹中，所以我必须将文件从资源文件夹复制到目录文件夹，如下所示：

func copyDB() -> Bool {
    let fileManager = FileManager.default
    let documentsUrl = fileManager.urls(for: .documentDirectory, in: .userDomainMask)
    var returnStatus: Bool = false

    guard documentsUrl.count != 0 else {
        print("Could not find documents url")
        return false
    }

    let finalDatabaseURL = documentsUrl.first!.appendingPathComponent(dbFileName)

    if !((try? finalDatabaseURL.checkResourceIsReachable()) ?? false) {
        print("DB does not exist in documents folder")

        let documentsURL = Bundle.main.resourceURL?.appendingPathComponent(dbFileName)

        do {
            try fileManager.copyItem(atPath: (documentsURL?.path)!, toPath: finalDatabaseURL.path)
        } catch let error as NSError {
            print ("Couldnt copy file to final location! Error:\(error.description)")
            returnStatus = false
        }
    } else {
        print ("Database file found at path: \(finalDatabaseURL.path)")
        returnStatus = true
    }

    return returnStatus
}

下面是 OpenDatabase 的代码

func openDB() -> Bool {
    let fileManager = FileManager.default
    let documentsUrl = fileManager.urls(for: .documentDirectory, in: .userDomainMask)
    let dbPath = documentsUrl.first!.appendingPathComponent(dbFileName)
    let database = FMDatabase(url: dbPath)

    var returnStatus: Bool = false

    if (self.copyDB() == false) {
        returnStatus = false
    } else {
        if (!database.open(withFlags: 1)) {
            print("Could not open database at \(dbPath.absoluteString)")
            returnStatus = false
        } else {
            self.database = database
            returnStatus = true
        }
    }

    return returnStatus
}

下面是执行查询的代码

func executeQuery(queryString:String) {
    print(queryString)
    do {
        if (database.open()){
            let results:FMResultSet = try database.executeQuery(queryString, values: nil)

            if results.next() == true {
                print(results)
            }
        }
    } catch let error as NSError {
        print(error.description)
    }
}

copyDB() 和 openDB() 工作正常，但是我尝试执行Query()，出现以下错误：

Error Domain=FMDatabase Code=1 "no such table: tableName" UserInfo={NSLocalizedDescription=no such table: tableName}

Answer 1

以下是有效的代码：

    func copyDataBase() -> Bool {
    let fileManager = FileManager.default
    var dbPath = ""

    do {
        dbPath = try fileManager.url(for: .applicationSupportDirectory, in: .userDomainMask, appropriateFor: nil, create: true).appendingPathComponent(dbFileName).path
    } catch {
        print(error.localizedDescription)
        return false
    }

    if !fileManager.fileExists(atPath: dbPath) {
        let dbResourcePath = Bundle.main.path(forResource: "dbName", ofType: "sqlite")
        do {
            try fileManager.copyItem(atPath: dbResourcePath!, toPath: dbPath)
        } catch {
            print(error.localizedDescription)
            return false
        }
    }
    return true
}

希望对有需要的人有所帮助

Answer 2

  Firstly Create FileManager Object. Get Path and check file is exist or not then copy items from db.
     func callForCopyDBAllObejct() -> Bool {
     let fileM = FileManager.default
     var dbPath = nil

    do {
      dbPath = try fileM.url(for: .applicationSupportDirectory, 
 in: .userDomainMask, appropriateFor: nil, create: 
   true).appendingPathComponent(dbFileName).path
   } catch {
      print(error.localizedDescription)
       return false
   }

     if !fileM.fileExists(atPath: dbPath) {
       let dbResourcePath = Bundle.main.path(forResource: "dbName", 
   ofType: "sqlite")
       do {
         try fileM.copyItem(atPath: dbResourcePath!, toPath: 
    dbPath)
       } catch {
        print(error.localizedDescription)
        return false
       }
   }
   return true

}