How to migrate a realm database to an app group?

Question

Really excited about the recent addition of sharing Realm data between apps and extensions. The documentation details how to set the default realm to the app group directory, I've got that working.

Here's what I'm stuck on -- what's the best way to transfer the old database to the new location in the app group?

Answer 1

Based on @segiddins comment, I decided to go with moving the old database to the app group using NSFileManager:

    let fileManager = NSFileManager.defaultManager()

    //Cache original realm path (documents directory)
    let originalDefaultRealmPath = RLMRealm.defaultRealmPath()

    //Generate new realm path based on app group 
    let appGroupURL: NSURL = fileManager.containerURLForSecurityApplicationGroupIdentifier("group.AppGroup")!
    let realmPath = appGroupURL.path!.stringByAppendingPathComponent("default.realm")

    //Moves the realm to the new location if it hasn't been done previously
    if (fileManager.fileExistsAtPath(originalDefaultRealmPath) && !fileManager.fileExistsAtPath(realmPath)) {

        var error: NSError?
        fileManager.moveItemAtPath(originalDefaultRealmPath, toPath: realmPath, error: &error)

        if (error != nil) {
            println(error)
        }
    }

    //Set the realm path to the new directory
    RLMRealm.setDefaultRealmPath(realmPath)

Answer 2

Hope this will help other reader.

As discussed in https://github.com/realm/realm-cocoa/issues/4490, you can set app group path with below code and use File Manager to move existing db as mention above.

var config = Realm.Configuration()
config.fileURL = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: appGroupIdentifier)!.appendingPathComponent(dbFilename)
Realm.Configuration.defaultConfiguration = config