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Using dummy headers

info

This guide was written for flutter_rust_bridge v1, thus some content may be outdated. The quickest approach to integrate is to follow the one-click approach in flutter_rust_bridge's quickstart page.

flutter_rust_bridge_codegen created a C header which lists all the exported symbols from our library, then uses it so that Xcode won't strip the symbols.

Add ios/Runner/bridge_generated.h (or macos/Runner/bridge_generated.h) to the project, either by dragging it onto the project tree or via the Add Files to "Runner"... menu option.

Switch to the Build Phases tab and drag the bridge_generated.h file over to the Copy Bundle Resources section, if it isn't already present.

iOS​

Next, add this line to ios/Runner/Runner-Bridging-Header.h:

+#import "bridge_generated.h"

and in ios/Runner/AppDelegate.swift:

 override func application(
     _ application: UIApplication,
     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
 ) -> Bool {
+    let dummy = dummy_method_to_enforce_bundling()
+    print(dummy)
     ..
 }

It is important that you use the result of dummy_method_to_enforce_bundling() (like in the example above), otherwise the symbols might still get stripped.

Stripping iOS symbols​

If you release your app through App Store, the steps above might not be sufficient. In that case you need to modify how Xcode strips the symbols:

  1. In Xcode, go to Target Runner > Build Settings > Strip Style.
  2. Change from All Symbols to Non-Global Symbols.

Ref: https://docs.flutter.dev/development/platform-integration/ios/c-interop#stripping-ios-symbols

MacOS​

Flutter on MacOS does not use headers by default, so let's go ahead and add one ourselves. In the Build Settings tab, set the Objective-C Bridging Header to be Runner/bridge_generated.h.

Also, head over to the Build Phases tab, Bundle Framework section and add your $crate.dylib by clicking the plus button. This includes your dynamic library file in your app package.

Finally, use dummy_method_to_enforce_bundling somewhere within macos/Runner/AppDelegate.swift, as long as Xcode does not consider it dead code.

For multi-blocks

If there are multi-blocks:

  • For iOS, just add the 1st generated block-header files in Runner-Bridging-Header.h.
  • For MacOS, just add the 1st generated block-header files as Objective-C Bridging Header.

For all cases, the AppDelegate.swift should be the same as that in the single-block case. related issue