How to use a populated SQLite database with SharkORM - ios

Question

I am an Android developer who start learning iOS development. I am still learning so please expect some basic questions here.
Here is what I try to achieve: I have an existing SQLite database (kanadb.db) and I would like to use it in my iOS application. I would like to use an ORM to work with this database (the access will be read only) so I dropped the .db file in the project folder and did this in AppDelegate.swift:
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
SharkORM.setDelegate(self)
SharkORM.openDatabaseNamed("kanadb")
// -- Test --
// Try to load some data from the database
let results: SRKResultSet = Info.query().fetch()
print(results)
// ----------
return true
}
But it is not working. I noticed that it creates a new kanadb.db in a folder somewhere in the file system. Something similar is done in Android, at startup we need to see if the DB already exist in the app folder and if not, copy the database from the bundle to the app folder. It looks like I have to do something similar here but I don't know how, as I am still new to iOS.
Can anyone give me some hints / code snippet to would point me to the correct direction?
Thank you!

Answer 1

I just found the solution, so I will post it here, it can be useful for someone.
So, as I expected, we have to copy the bundled database to the document folder of the application. However, the database file must be available in the target, so we have to select it in the files list (in XCode) and check Target Membership.
Then, copy it to the Document folder before using it:
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
let DB_NAME = "kanadb"
let DB_EXTENSION = "db"
do{
let databasePath = Bundle.main.url(forResource: DB_NAME, withExtension: DB_EXTENSION)
let documentsDirectory = try FileManager.default.url(for: FileManager.SearchPathDirectory.documentDirectory, in:FileManager.SearchPathDomainMask.userDomainMask, appropriateFor:nil, create:false)
let destination = documentsDirectory.appendingPathComponent(DB_NAME + "." + DB_EXTENSION)
_ = try FileManager.default.copyItem(at: databasePath!, to:destination)
} catch {
// TODO: Catch the errors more gracefuly
print("Couldn't copy the database to the document folder")
}
// Override point for customization after application launch.
SharkORM.setDelegate(self)
SharkORM.openDatabaseNamed(DB_NAME)
// -- Test --
// Try to load some data from the database
let results: SRKResultSet = Info.query().fetch()
print(results)
// ----------
return true
}
And that's it! Now it may be a good idea to check if the database already exist in the Document folder of the app to avoid doing that everytime we launch the app.