WatchOS compatibility

[zifeo]

Currently: error: While building for watchOS Simulator, no library for this platform was found in '/Users/USER/Library/Developer/Xcode/DerivedData/kite_and_work-fusbjqcfyjsuraegryjkczwuruaj/SourcePackages/artifacts/powersync-kotlin/PowerSyncKotlin/PowerSyncKotlin.xcframework'

Is this supported?

[simolus3]

At the moment, we support iOS only. We don't want things to stay that way forever (adding macOS support is in progress, we're currently trying to work our way around some limitations of our dependencies to enable that).

Generally, it looks like there isn't anything that fundamentally prevents watchOS / tvOS support either (our core extension is written in Rust which should support this, and our upstream Kotlin multiplatform dependencies used to implement the Swift SDK should support this too). So while it's not on our roadmap at this point (you might be the first one asking for it), I think it's something that we could support in the future given enough interest.

[zifeo]

@simolus3 Would you share some technical direction? I am happy to investigate & contribute back.

[simolus3]

Awesome, thanks for offering to help! Basically, most of the Swift SDK is either:

• using this loadable extension for SQLite. The extension is re-used across all our PowerSync SDKs and contains code to apply downloaded changes from the sync service as well as tracking local writes. This is written in Rust and we ship this as an xcframework on Apple platforms (currently iOS and macOS). We're already using Rust nightly so the tier 3 targets for watchOS shouldn't be a problem. To me, it sounds like adding watchOS support would involve adding compiler flags, installing these targets for CI (here and here) and finally changing our xcframework build script to include the new platforms.
• implemented in Kotlin. Adding watchOS support here should be a lot easier after macOS support gets merged. I assume it would simply involve adding new targets to this block (we need watchosSimulatorArm64, watchosX64, watchosArm32 (okay maybe we can skip that one), watchosArm64 and watchosDeviceArm64). Our SDK compiles and links SQLite statically on Apple platforms, so this block needs entries for watchOS as well. We also need to test our SDK in the simulator, which would involve linking our framework here.

So there are quite a few steps, but I hope they're all rather straightforward (I'm also happy to give more pointers or take care of these steps, but as I've said it's not a huge priority for us at the moment). It might be that watchOS doesn't support some of the platform APIs we need, but from a quick look the most concerning one is our sync client which uses an HTTP stream that should be supported on watchOS as well.

[zifeo]

@simolus3 I just added an attempt for 1. though I am not convinced of the approach: https://github.com/powersync-ja/powersync-sqlite-core/pull/73/files. Feedback is appreciated.

[simolus3]

Version 1.2.1 of our Swift SDK should support all modern watchOS targets. We're running unit tests on a Simulator for that, so most things should work. Unfortunately I didn't have time to test this on an actual app / watch yet, so there's a chance something related to the networking / streaming sync process could still fail. I hope I get to that soon, but generally watchOS should work with the latest version.

[asiergmorato]

When building a watchOS app that includes PowerSync as a dependency, the build fails during the validation phase with the following error:

Framework /Users/asiergmorato/Library/Developer/Xcode/DerivedData/FitWoody-bcdjjvcqjheamafhhxdwwamgwpzg/Build/Products/Debug-watchsimulator/FitWoody-Watch.app/Frameworks/powersync-sqlite-core.framework contains Versions/Current/Resources/Info.plist, expected Info.plist at the root level since the platform uses shallow bundles

[simolus3]

Thanks, I'll look into that. Were you able to run this on a simulator?

[asiergmorato]

Not at all. It doesn't build in the simulator or on the real device.

[simolus3]

I think the constraint about the wrong xcframework layout isn't relevant for simulators - or at least I'm able to link the core extension on a watchOS simulator. If you select a simulator as a target in xcode and run the app, does that work for you?

We still have to fix the issues for physical devices, but I managed to get things running on a simulator so I'm wondering if you're running into other issues with that.

[simolus3]

And from another look I've also gotten weird errors with version 1.2.0 of the Swift SDK but in my test project, those have been fixed in 1.2.1.

[asiergmorato]

Hi! I get the same error no matter what I build for:

Validate /Users/asiergmorato/Library/Developer/Xcode/DerivedData/FitWoody-bcdjjvcqjheamafhhxdwwamgwpzg/Build/Products/Debug-watchsimulator/FitWoody-Watch.app (in target 'FitWoody-Watch' from project 'FitWoody')
    cd /Users/asiergmorato/Developer/FitWoody
    builtin-validationUtility /Users/asiergmorato/Library/Developer/Xcode/DerivedData/FitWoody-bcdjjvcqjheamafhhxdwwamgwpzg/Build/Products/Debug-watchsimulator/FitWoody-Watch.app -shallow-bundle -infoplist-subpath Info.plist

error: Framework /Users/asiergmorato/Library/Developer/Xcode/DerivedData/FitWoody-bcdjjvcqjheamafhhxdwwamgwpzg/Build/Products/Debug-watchsimulator/FitWoody-Watch.app/Frameworks/powersync-sqlite-core.framework contains Versions/Current/Resources/Info.plist, expected Info.plist at the root level since the platform uses shallow bundles (in target 'FitWoody-Watch' from project 'FitWoody')

I have version 1.2.1 of the Swift SDK but 0.4.1 of the powersync-sqlite-core

I reseted all package caches. As soon as I add the library to the watchOS target the project doesn't compile.

If there is something I can try to help you out don' hesitate to ask.

[simolus3]

If there is something I can try to help you out don' hesitate to ask.

Thanks! Can you reproduce this issue in a small / independent project you could share with us? I've tried creating a new project in XCode, adding a watchOS target, using some dummy PowerSync functionality in there and archiving the app for release on watchOS. At no point did I get any error, but I also only see the builtin-validationUtility log for my demo project and not for dependencies - so there might be a slightly different build setup that causes my project to work despite something being broken in PowerSync.

[asiergmorato]

According to Claude here is what's happening:

Your powersync-sqlite-core.framework currently has a deep bundle structure (macOS/iOS style):

powersync-sqlite-core.framework/
├── Versions/
│   └── Current/
│       └── Resources/
│           └── Info.plist

But watchOS requires a shallow bundle structure:

powersync-sqlite-core.framework/
├── Info.plist (at root level)
├── powersync-sqlite-core (binary)
└── Headers/ (if any)

Solutions

Option 1: Create watchOS-specific build target

In your framework's Xcode project:

1. Add a new target specifically for watchOS
2. Set the target's "Bundle Structure" to "Shallow Bundle" in Build Settings
3. This will automatically create the correct structure for watchOS

Option 2: Configure Build Settings for universal framework

If you want one framework to work across platforms:

1. In your framework target's Build Settings, find "Generate Info.plist File"
2. Set different bundle structures per platform using conditions:

   SHALLOW_BUNDLE[sdk=watchos*] = YES
   SHALLOW_BUNDLE[sdk=watchsimulator*] = YES
   

Option 3: Use XCFramework (Recommended)

Create an XCFramework that includes separate builds for each platform:

xcodebuild -create-xcframework \
    -framework path/to/ios/powersync-sqlite-core.framework \
    -framework path/to/watchos/powersync-sqlite-core.framework \
    -framework path/to/macos/powersync-sqlite-core.framework \
    -output powersync-sqlite-core.xcframework

Option 4: Check platform compatibility

Consider whether your SQLite framework actually needs to run on watchOS. If not:

1. Mark it as unavailable for watchOS in your Package.swift or podspec
2. Add platform availability annotations in your Swift code:

   #if !os(watchOS)
   // Code that doesn't work on watchOS
   #endif