ios - 尝试访问 ios 时，sqlite 预填充数据库为空

Question

我是 Swift 3 和 ios 的新手，之前编写过访问数据库的 Android 程序。当前的问题是数据库预填充了 10 个表，但是，当我尝试访问数据库时，模拟器或设备中都没有表，因此无法访问数据。我搜索了论坛和互联网，但只能找到检查数据库是否存在的信息。 sqlite 包装器是正在使用的 FMDB。

代码:

override func viewDidLoad() {
    super.viewDidLoad()
let filemgr = FileManager.default
let dirPaths = filemgr.urls(for: .documentDirectory, in: .userDomainMask)   

 let destPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first!

databasePath = dirPaths[0].appendingPathComponent("level24.db").path

 print(databasePath)

 let fullDestPath = URL(fileURLWithPath: destPath).appendingPathComponent("level24.db")

 let bundleDatabasePath = Bundle.main.path(forResource: "level24", ofType: ".db")

 var level2DB = FMDatabase(path: databasePath as String)


  if filemgr.fileExists(atPath: fullDestPath.path){
  print("Database file is exist")
  print(filemgr.fileExists(atPath: bundleDatabasePath!))

  }else{
  filemgr.replaceItemAt(databasePath, withItemAt: bundleDatabasePath.path)
  }



level2DB = FMDatabase(path: databasePath as String)
 if (level2DB?.open())!{
          print("Database is open")

var querySQL = "SELECT * FROM sqlite_master WHERE name = '\(tblName)' and type='table'"
let results:FMResultSet? = level2DB?.executeQuery(querySQL, withArgumentsIn:nil)

        if (results == nil){
            print("Results = \(results)")

            do{
                try filemgr.copyItem(atPath: bundleDatabasePath!, toPath: fullDestPath.path)
            }catch{
                print("\n",error)
            }

        }
    print("Results after = \(results)")

    let querySQL2 = "SELECT QUESTION FROM tblSani WHERE _ID = 5"

    let results2:FMResultSet? = level2DB?.executeQuery(querySQL2, withArgumentsIn:nil)

    print(results2?.string(forColumn: "QUESTION") as Any)

    }
}

输出是:

 /Users/***/Library/Developer/CoreSimulator/Devices/4F511422-2F86-49BF-AB10-5CA74B9A7B40/data/Containers/Data/Application/58DD87EB-C20F-4058-B9BC-CCD7ECEEFA98/Documents/level24.db
Database is open
Results after = Optional(<FMResultSet: 0x608000245220>)
2017-04-05 21:09:26.833 Level 2[3161:210849] DB Error: 1 "no such table: tblSani"
2017-04-05 21:09:26.833 Level 2[3161:210849] DB Query: SELECT QUESTION FROM tblSani WHERE _ID = 5
 2017-04-05 21:09:26.834 Level 2[3161:210849]DBPath: /Users/***/Library/Developer/CoreSimulator/Devices/4F511422-2F86-49BF-AB10-5CA74B9A7B40/data/Containers/Data/Application/58DD87EB-C20F-4058-B9BC-CCD7ECEEFA98/Documents/level24.db
nil

如果您能帮助我找到解决问题的方法，我们将不胜感激。

Answer 1

经过数小时的努力，我想出了这个解决方案:这被放入 AppDelegate.swift 并将在应用程序启动时检查

代码:

var filemgr = FileManager.default
static let dirPaths = FileManager().urls(for: .documentDirectory, in: .userDomainMask)
static let destPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first!

var databasePath = dirPaths[0].appendingPathComponent("level24.db").path

static let fullDestPath = URL(fileURLWithPath: destPath).appendingPathComponent("level24.db")

static let bundleDatabasePath = Bundle.main.path(forResource: "level24", ofType: ".db")

//function to check if dbase exists
func checkdbase(){

    print(databasePath)

    print("Full path = \(AppDelegate.fullDestPath)")

    var level2DB = FMDatabase(path: databasePath as String)


    if filemgr.fileExists(atPath: AppDelegate.fullDestPath.path){

        print("Database file is exist")
        print(filemgr.fileExists(atPath: AppDelegate.bundleDatabasePath!))
        print("bundle = \(AppDelegate.bundleDatabasePath)")

        let level2DB = FMDatabase(path: databasePath as String)

        if (level2DB?.open())!{
            print("Database is open")

       // use a select statement for a known table and row
   let querySQL2 = "SELECT * FROM tblSani WHERE _ID = 5"

            let results:FMResultSet? = level2DB?.executeQuery(querySQL2, withArgumentsIn:nil)

                if results?.next()==true{
                    print("Database has tables")

                }else{
                    print("Database no tables")
                    removeDB()

                }

        }
    }else{
        removeDB()
    }
}

//function to remove existing dbase then unpack the dbase from the bundle
func removeDB(){

    do{
        try filemgr.removeItem(atPath: AppDelegate.fullDestPath.path)
        print("Database removed")

    }catch {
        NSLog("ERROR deleting file: \(AppDelegate.fullDestPath)")
    }

    do{
        try filemgr.copyItem(atPath: AppDelegate.bundleDatabasePath!, toPath: AppDelegate.fullDestPath.path)
        print("Databse re-copied")
    }catch{
        print("\n",error)
    }

}

从 AppDelegate 'didFinishLaunchingWithOptions' 调用函数

checkdbase()

如果你能改进这个答案，请帮助其他可能有同样问题的人