How to keep default realm data after add sync?

MongoDB Atlas App Services & Realm
1

I have an app using offline default Realm and I plan to adopt MongoDB Realm for data synchronization.

While reading the Realm tutorial source code. It uses a default realm in signIn method, realm-tutorial-ios-swift/WelcomeViewController.swift at ca9fd52acabef416c0b7c7e538e2601a1dbf2b20 · mongodb-university/realm-tutorial-ios-swift · GitHub.

20210816-223710@2x
20210816-223710@2x1298×554 76.5 KB

The default configuration got changed a bit and in the comment, it said “This configuration step is not really needed, but if we add Sync later, this allows us to keep the tasks we made.”

The part I don’t understand is how these changes would keep the tasks? would manually copy data from the default realm to a synced realm still need?

2

I ran the project for a couple of times with the default configuration, despite the realm database path keep changing the data added into the database still got persisted

>>> DEBUG: [DCRealm:Init] file:///Users/x/Library/Developer/CoreSimulator/Devices/9E9B2536-A579-4C11-8197-702F52570626/data/Containers/Data/Application/5B55F08C-61EF-486C-BCFA-2DB11C21A603/Documents/default.realm
>>> DEBUG: [DCRealm:Init] file:///Users/x/Library/Developer/CoreSimulator/Devices/9E9B2536-A579-4C11-8197-702F52570626/data/Containers/Data/Application/643D0506-BC86-4767-9516-471043324E20/Documents/default.realm
>>> DEBUG: [DCRealm:Init] file:///Users/x/Library/Developer/CoreSimulator/Devices/9E9B2536-A579-4C11-8197-702F52570626/data/Containers/Data/Application/CF7999F3-FED9-44D7-9501-D9265CF25A11/Documents/default.realm
>>> DEBUG: [DCRealm:Init] file:///Users/x/Library/Developer/CoreSimulator/Devices/9E9B2536-A579-4C11-8197-702F52570626/data/Containers/Data/Application/746CAA4D-2BB3-438C-AB4C-038808508F22/Documents/default.realm
>>> DEBUG: [DCRealm:Init] file:///Users/x/Library/Developer/CoreSimulator/Devices/9E9B2536-A579-4C11-8197-702F52570626/data/Containers/Data/Application/F3622040-05E4-42BD-8343-230D3EC31E6C/Documents/default.realm
>>> DEBUG: [DCRealm:Init] file:///Users/x/Library/Developer/CoreSimulator/Devices/9E9B2536-A579-4C11-8197-702F52570626/data/Containers/Data/Application/69C06F4E-5958-4D97-9FF0-ED9A17F76C1D/Documents/default.realm