[React Fabric] Updating Build Configuration (CocoaPods, .xcodeproj, gradle)

For Discussion

Various parts of React Fabric code are available in github, but we need to upgrade a bunch of build configuration to make it build properly on iOS and Android. This will involve reflecting the BUCK targets for various parts of Fabric into the 3 areas:

• React.podspec (iOS) – note that we had partial configs already, but very outdated.
• React.xcodeproj (iOS)
• build.gradle (Android)

An initial version of the update could just be manually sync’ed configs for .podspec, .xcodeproj, and .gradle.

But for the future, some ideas include:

• Have BUCK generate the relevant .podspec, .xcworkspace, or .gradle – this may require a bunch of work via buck project
• etc

Requirements

• Have RNTester built with Fabric symbols correctly (iOS/Android to start)
• Upgraded version of Folly - see https://github.com/facebook/react-native/issues/20302
  • Note that we’re on v2018.10.22 already (https://github.com/facebook/react-native/pull/21976, https://github.com/facebook/react-native/pull/21977)

cc @mdvacca, @shergin

[fkgozali]

I believe the issue is due to AppDelegate.m not being an Objective-C++ file

Ah, yeah a bunch of files need to become .mm instead. I think that’s an ok requirement though, given the increasing number of C++ we’re adding. That said, if AppDelegate.m needs to be AppDelegate.mm, let’s switch it over. If you find more .m files to be converted to .mm, let’s note them here as well.

[ericlewis]

Here is my WIP: https://github.com/ericlewis/react-native/commits/fabric

• pod files seem “done”
• renaming Float.h fixes CGFloat issue. Conflicts somewhere.

Compiling this branch’s RNTester with RCTFabric & RCTFabricSample works, it links correctly! But you must remove the fabric switch component refs, bc they ref something called rncore that appears to be missing.