Migration from SwiftData #195

bradr3d · 2025-09-17T21:32:03Z

bradr3d
Sep 17, 2025

Hi! This is widely touted as a good alternative to SwiftData, but there's no documentation on how to potnetially migrate from SwiftData to this? Is it possible?

mbrandonw · 2025-09-17T22:22:14Z

mbrandonw
Sep 17, 2025
Maintainer

Hi @bradr3d, we have no documentation on this because it's quite a large undertaking to completely change out the underlying persistence and querying mechanism for your app, regardless of the libraries involved. It would be equally hard to migrate a SQLiteData app to a SwiftData app too.

It's technically possible, but it's going to be difficult. The only approach that comes to mind is to recreate all of your SwiftData models as SQLite tables and then perform a one-time migration that loads all of your SwiftData rows into memory and insert them into your new SQLite tables.

Maybe others in the community have some other ideas.

2 replies

davidakoontz May 25, 2026

I'm going to rely on CSV - use SwiftData export to CSV (which is just a basic transaction list of buy or sell stock).
Then switch to the new App and import the CSV.

tiendq Oct 21, 2026

Hi @mbrandonw,

I also think one-time migration is only way but I'm not sure how it works in this situation:

Let's say current app version is 2.0 and I decide to migrate it to SQLiteData and versioned as 2.1 (v2.1 has first SQLite database schema for new installations, initialized with migrator.registerMigration("v1")).
I write code to move data from SwiftData (v2.0) to SQLiteData (v2.1), I want there is only one migration between database schemas from SwiftData (v2.0) to SQLiteData (v2.1).
Let's say more database schema changed in v2.2 with migrator.registerMigration("v2").

So how does this code work? Since SQLiteData migration process run once with try migrator.migrate(database) after all migrations are registered.

migrator.registerMigration("v1")
migrateSwiftDataToSQLiteData()
migrator.registerMigration("v2")

Thank you,

davidakoontz · 2026-04-08T02:19:45Z

davidakoontz
Apr 8, 2026

I'm pondering the SwiftData -> SQLiteData for my App (Stock Portfolio Equity Curve - PortfolioEC for short name).

My first few thoughts have been NO Migration - just make an incompatible new version.

this works for me and my app as I'm looking a ZERO paid subscription (no users yet - that a different problem).
this leaves me with a question: How do I clean up the possible old DB on a trial users device?
o I assume I could look for the old SwiftData DB (App location) and delete it in the new version.
o I could just ignore and forget it ... only a few 100 KB - wonder if Apple has a reaper policy?

A manual CSV Export & CSV Import

this is a very real possibility as the majority of user data is the Stock Transaction which I've got a CSV Export / Import function already. Most of the DB is with the daily snapshots of account aggregate totals.
still leaves the question of old DB clean up

Delete old version App - Fresh Install new version App

given Zero Users - this is a clear winner
still leaves the question of old DB clean up

Upgrade old version 2.xxx to new version 3.xx

does the App Store deal with removing the DB and User Defaults? (I think so...Testable)
I've attempted this path.... the new App works... but Apple's CloudKit DB web tool still shows existing DB records
o https://icloud.developer.apple.com/dashboard/

I will be investigating some/all of these options. But open to other's experience/knowledge.

David Koontz
(PortfolioEC App)

1 reply

davidakoontz May 25, 2026

I used OpenAI's Xcode Codex to swap DBs... it took a good 3 weeks of work, Codex performed very well.
I've now used the new SQLiteData for over a month and will release a Ver 3 of the app Portfolio Equity Curve very soon.
My target is before June.
It will be a complete replacement - no porting of the existing DB. One could of course export CSV upgrade App and import CSV.

hungri-yeti · 2026-05-28T04:38:55Z

hungri-yeti
May 28, 2026

I just finished a migration. Roughly, the steps were:

abstract the data layer to a protocol to isolate SwiftData from the rest of the app
add a LegacySwiftDataMigration to move the data over
move SQLIteData into viewModels etc.

I used a combination of claude/codex, one for writing up a plan the other for implementing. Took a good week and maxed out my session tokens more than once.

0 replies

tiendq · 2026-10-21T01:22:46Z

tiendq
Oct 21, 2026

@mbrandonw

I found this blog post during googling yesterday, and mentioned app name caught my eyes since I remembered I saw it somewhere (here). I just wondered if this guy think he is the red guy then it's too risky to switch to SQLiteData, so why does he not stay with SwiftData to benefit from "unspoken infrastructure of SwiftData on iCloud"? And pay hidden costs for those safety nets, for example Fatbobman recently found that even you select a few columns SwiftData still fetch all columns in its queries.

https://www.theswiftdojo.com/a-managed-db-in-icloud

0 replies

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Migration from SwiftData #195

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bradr3d Sep 17, 2025

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mbrandonw
Sep 17, 2025
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davidakoontz
Apr 8, 2026

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May 28, 2026

tiendq
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