Brownfield usage of Fabric with Swift #143
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I am trying to activate Fabric within an existing iOS app to use Turbo Native Modules. The app was created using Swift, but there are no examples of changes that must be made to use Fabric when using Swift. What I've tried so far:
After that I ended up with this import UIKit
import React
import RCTFabric
@main
class AppDelegate: UIResponder, UIApplicationDelegate, RCTBridgeDelegate {
func sourceURL(for bridge: RCTBridge!) -> URL! {
#if DEBUG
return URL(string: "http://localhost:8081/index.bundle?platform=ios")
#else
return Bundle.main.url(forResource: "main", withExtension: "jsbundle")
#endif
}
static var bridge: RCTBridge?
#if RN_FABRIC_ENABLED
static var bridgeAdapter: RCTSurfacePresenterBridgeAdapter?
#endif
var window: UIWindow?
#if RN_FABRIC_ENABLED
var bridgeAdapter: RCTSurfacePresenterBridgeAdapter?
var reactNativeConfig: Unmanaged<ReactNativeConfig>?
var contextContainer: Unmanaged<ContextContainer>?
#endif
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.//
#if RN_FABRIC_ENABLED
contextContainer = Unmanaged.passRetained(ContextContainer())
reactNativeConfig = Unmanaged.passRetained(EmptyReactNativeConfig())
contextContainer?.takeUnretainedValue().insert("ReactNativeConfig", reactNativeConfig?.takeUnretainedValue())
bridgeAdapter = RCTSurfacePresenterBridgeAdapter(bridge: bridge, contextContainer: contextContainer?.takeUnretainedValue())
AppDelegate.bridge.surfacePresenter = bridgeAdapter?.surfacePresenter
#endif
return true
}
...
}If I try to build the project after running If any more information is needed, I am happy to provide it. |
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Replies: 2 comments 9 replies
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Hi @flokol120! Unfortunately, Fabric cannot be used with Swift yet. You can create TurboModules in Swift, adding a thin wrapper of ObjectiveC++ though. We have prepared examples here. Look at the table in the README for more information. |
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Hi @jdbarrera, thanks for the question. It is not possible to have a base class in C++ and extends that in Swift. Inheritance between languages is not supported by the C++/Swift interop. For your specific error, I should see the stack trace and the error to be able to help, but it is definitely a very advanced/experimental |
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Thanks for the reply @cipolleschi ! Would I be able to convert my swift files to objective-c instead? And then inherit the c++ app delegate and extend it that way? Also, when Fabric becomes the default, are you planning on having swift support at that time? |
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Hi @jdbarrera!
Of course, that's possible! That's actually our default setup: the AppDelegate in a new app is an Objective-C++ class which inherit from the Technically, you might be able to even keep your AppDelegate in swift, if you create an indirection layer. Something like: The important point is that the ObjCAppDelegate must not have any C++/ObjC++ symbol in the header file.
Swift support is something we care about, but we need to do some steps to prepare it. I can't say how long it will take to get there, but it is a topic we discuss regularly, so, as soon as it will be feasible, we will tackle the problem for sure. |
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I think that from 0.74 it might be possible to make Swift inherit directly from RCTAppDelegate. That's what we are doing in React Native visionOS by default and I've upstreamed some fixes to make it possible in core (I'm not sure if they got picked for the release). |
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Thanks for the info! I will likely be revisiting this in a week or two so I'll let you know if I have any luck getting it to work |
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Take a look at https://github.com/microsoft/react-native-test-app , at least the macOS setup uses Swift for the AppDelegate and therefore probably also iOS, I just haven't tested it with iOS. But they do quite some interesting stuff there! |
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Hi @flokol120! Unfortunately, Fabric cannot be used with Swift yet.
There are some architectural changes we need to apply to our C++ layer in order to make it work properly with Swift.
You can create TurboModules in Swift, adding a thin wrapper of ObjectiveC++ though. We have prepared examples here. Look at the table in the README for more information.