Fixing "Called object type 'facebook:🐬:SocketCertificateProvider' is not a function or function pointer" in Xcode 15.3

Problem Statement

When building a React Native project (version 0.71.8) in Xcode 15.3, you may encounter a critical build failure with the error message:

"Called object type 'facebook:🐬:SocketCertificateProvider' is not a function or function pointer"

This error occurs due to a header file conflict in the Flipper debugging tool used by React Native. Xcode 15.3 introduced stronger type safety checks that expose a missing include in Flipper's certificate provider implementation. The issue specifically affects these file paths:

ios/Pods/Flipper/xplat/Flipper/FlipperTransportTypes.h
ios/Pods/Flipper/xplat/Flipper/SocketCertificateProvider.h

Without fixing this header issue, your React Native project will fail to build on both simulators and physical devices when using Xcode 15.3 or later.

Recommended Solutions

1. Upgrade Flipper to version 0.250.0 (Optimal Solution)

The most sustainable solution is to upgrade Flipper to a compatible version that includes the necessary fixes. Modify your ios/Podfile:

use_react_native!(
  # ... other configurations ...,
  :flipper_configuration => FlipperConfiguration.enabled(['Debug'], { 'Flipper' => '0.250.0' })
)

If your configuration uses the alternative syntax:

use_flipper!({ 'Flipper' => '0.250.0' })

After updating, run:

npx pod-install

This version resolves the header conflict while maintaining compatibility with React Native's debugging tools.

2. Temporary Manual Fix

If you can't upgrade immediately, add the missing include to the header file:

1. Open ios/Pods/Flipper/xplat/Flipper/FlipperTransportTypes.h
2. Add this include at the top:

#include <functional>

3. The modified header should look like:

#include <functional>
#include <string>

namespace facebook {
namespace flipper {
// ... existing code ...
} // namespace flipper
} // namespace facebook

This resolves the immediate build error but will be overwritten when you run npx pod install.

3. Automated Fix via Podfile (Persistent)

Add this script to your Podfile to automatically patch the header during pod installation:

post_install do |installer|
  # ... existing code ...
  
  installer.pods_project.targets.each do |target|
    if target.name == 'Flipper'
      file_path = File.join(installer.sandbox.root, 'Pods/Flipper/xplat/Flipper/FlipperTransportTypes.h')
      if File.exist?(file_path)
        contents = File.read(file_path)
        unless contents.include?('#include <functional>')
          File.write(file_path, "#include <functional>\n" + contents)
        end
      end
    end
  end
end

After adding this, run:

npx pod-install

4. Command Line Fix (CI/CD Friendly)

For automation environments like CI/CD pipelines, use this terminal command:

FLIPPER_FILE="ios/Pods/Flipper/xplat/Flipper/FlipperTransportTypes.h"
if ! grep -q "#include <functional>" "$FLIPPER_FILE"; then
  sed -i '' '1s/^/#include <functional>\n/' "$FLIPPER_FILE"
fi

Important Notes

1. Always delete your ios/Pods directory and run npx pod-install after updating the Podfile
2. Perform a full Xcode clean (Product > Clean Build Folder) after making changes
3. The manual fix is overwritten by npx pod install

Explanation

The root cause is a missing C++ standard library header in Flipper's implementation. Xcode 15.3 requires explicit inclusion of <functional> for std::function definitions.

• Flipper < 0.250.0: Relies on transitive includes that fail under Xcode 15.3's stricter headers
• Solution effectiveness:
  • Upgrade: Fixes root cause permanently
  • Podfile hook: Survives pod install
  • Manual edit: Quick fix during development
  • ❌ Not Recommended: Disabling Flipper (use_flipper!()) removes debugging capabilities

By upgrading Flipper or implementing the persistent solution, you ensure ongoing compatibility for both local development and continuous integration environments. The React Native team is aware of this issue, making upgrades the most future-proof solution.