xcode 10 error: multiple commands produce - react native

I have resolved my issue in Xcode 10.2 through below steps:

change the build system to Legacy

File > Workspace Settings > Build System > Legacy Build System.

My solution was in removing all that installer.pods_project.targets.each do |target| ... fixes from Podfile also I had pod 'React', :path => '... which I also removed. So my Podfile now looks like this

require_relative '../node_modules/react-native/scripts/react_native_pods'
require_relative '../node_modules/@react-native-community/cli-platform-ios/native_modules'

platform :ios, '12.4'

target 'AppName' do
  config = use_native_modules!

  use_react_native!(
    :path => config[:reactNativePath],
    :hermes_enabled => false
  )

  use_flipper!()

  post_install do |installer|
    react_native_post_install(installer)
  end
end

Default react-native Podfile

I was migrating from react-native 0.59 to 0.64

For those using React Native and Cocoapods

The issue was produced by some libRN...a files. I fixed it by removing some of them like libRNScreens.a and libRNGestureHandler.a from Build Phases -> Link Binary with Libraries since they were already being referenced from another libraries. Others had to be replaced by their Pod version like libRNDeviceInfo.a:

I fixed it by upgrading cocoapods to the latest version:

1. Close Xcode project.
2. Upgrade cocoapods to latest version - run "sudo gem install cocoapods"
3. Follow steps here to remove existing pods
4. Run "pod install" in the project directory