fix(apple): prepare react-native-codegen when using main (#711)

Author: tido64

ios/use_react_native-0.64.rb

@@ -1,3 +1,5 @@
+require 'open3'
+
 def include_react_native!(options)
   react_native, flipper_versions, project_root, target_platform = options.values_at(
     :path, :rta_flipper_versions, :rta_project_root, :rta_target_platform
@@ -8,6 +10,11 @@ def include_react_native!(options)
   use_flipper!(flipper_versions) if target_platform == :ios && flipper_versions
   use_react_native!(options)
 
+  # If we're using react-native@main, we'll also need to prepare
+  # `react-native-codegen`.
+  codegen = File.join(project_root, react_native, 'packages', 'react-native-codegen')
+  Open3.popen3('yarn', :chdir => codegen) if File.directory?(codegen)
+
   lambda { |installer|
     react_native_post_install(installer)
     if defined?(__apply_Xcode_12_5_M1_post_install_workaround)