Precompiled binary for React Native Core

[cipolleschi]

Starting from React Native 0.81, we are shipping React Native for iOS as a precompiled binary. This helps to reduce build times and build errors related to React Native.

We experimented and benchmarked how much time this initial precompiled binary for iOS is saving and, in our benchmarks, running on an M4 machine, iOS builds are roughly 8.3 times faster with the precompiled binary rather than by building from source.

Build Time [s]	With Precompiled binary	No Precompiled binary	Improvement [%]
Average	17.67	147.42	88.0 %
St. Deviation	0.99	18.77	94.72 %

This feature is still experimental, but we believe that it will improve the developer experience of all React Native users when they works on an iOS application.

The goal of this discussion is to track issues you might encounter when turning this feature on.

If you experience any problem with the precompiled binaries, please post a comment below this discussion.

How to use them

This feature is still experimental, so it is not turned on by default.
If you want to use them, you can install your pods by adding the RCT_USE_RN_DEP env variable:

RCT_USE_RN_DEP=1 RCT_USE_PREBUILT_RNCORE=1 bundle exec pod install

Alternatively, if you want to enable it for all the developers working on that, you can modify your Podfile like this:

if linkage != nil
  Pod::UI.puts "Configuring Pod with #{linkage}ally linked Frameworks".green
  use_frameworks! :linkage => linkage.to_sym
end

+ENV['RCT_USE_RN_DEP'] = '1'
+ENV['RCT_USE_PREBUILT_RNCORE'] = '1'

target 'HelloWorld' do
  config = use_native_modules!

Known limitations

We are currently aware of 2 knowns limitations, we are looking into solving.

Precompiled binaries does not work with Xcode 26 out of the box

Xcode 26 is still in Beta, and Apple changed the default value of the SWIFT_ENABLE_EXPLICIT_MODULES setting in the new version of the IDE.

The new default value is YES, and with this setting turned on, you'll see an error like this:

Module React_RCTAppDelegate not found

To use prebuilds with Xoce 26, you can turn off the SWIFT_ENABLE_EXPLICIT_MODULES in your app's Build Settings.

We will ship the proper fix in React Native 0.81.1

Can't debug React Native code

We are aware that it is not possible to step into React Native's internals when building your app using precompiled binaries. You can still debug your own native code.

Stepping into React Native's internal is a feature we would like to preserve when you are building your app in Debug mode, but we currently don't have a solution for this. If you need to debug a problem in your app you think is due to React Native code, you'll have to build your app from source, for the time being.

[christianbach]

First off—huge thanks for all the work on the new prebuilt flow in RN 0.81 🙌
It’s slick and everything worked great for us… until App Store Connect validation.

Repro (iOS):

• Enable the new prebuilt option
• Archive (Release) and Validate locally or upload to ASC
• Validation fails (screenshot attached)

Error (ASC / Xcode Validate):
Invalid CFBundleSupportedPlatforms value … contains an invalid value, [XRSimulator].
Happens for the resource bundles inside ReactNativeDependencies.framework:
…_boost.bundle, …_folly.bundle, …_glog.bundle.

What I’m seeing in the .xcarchive:

• ReactNativeDependencies.framework/Info.plist → CFBundleSupportedPlatforms = ["iPhoneOS"] ✅
• The nested *.bundle/Info.plist → CFBundleSupportedPlatforms = ["XRSimulator"] ❌
  (Apple rejects that in a shipping build.)

Workaround that unblocks TestFlight:

• During the build, remove CFBundleSupportedPlatforms from those resource bundle plists.
• Keep the main app (and actual device frameworks) at ["iPhoneOS"].
  After stripping the key from the bundles, validation/upload succeeds.

Screenshots

Validation using local Xcode:

CFBundleSupportedPlatforms inside ReactNativeDependencies_boost.bundle

[cipolleschi]

We were thinking about that, but we need apple accounts and set up all the infrastructure and we don't have capacity to do that right now, plus it will require a loto f paperwork with compliance and security to get the accounts and certificates and so on for this purpose.

[chrfalch]

Thanks for this report, @christianbach - I've managed to find the issue that caused this and a fix has been made :)

[christianbach]

Great looking forward to testing this out in 0.81.1 release.

[thymikee]

I can confirm 0.81.1 works 👍🏼

[christianbach]

same for us, great work!

[aleclarson]

I'm trying to install a React Native 0.81.1 app onto my iPhone, but am getting this error:

Failed to verify code signature of /var/installd/Library/Caches/com.apple.mobile.installd.staging/temp.FzDAYv/extracted/FooBar.app/Frameworks/ReactNativeDependencies.framework : 0xe800801c (No code signature found.)

The xcworkspace was generated by Expo 54 and I'm using a development signing certificate.

edit: Might be Expo's fault: expo/expo#39233 (comment)

[aleclarson]

The issue was entirely my fault. I had gone into the iOS SDK inside Xcode.app and edited a plist setting that inadvertently disabled code signing. 🤦