[Bug report] Undefined symbols for architecture x86_64 on Xcode build

Goals

We are getting several errors Undefined symbols for architecture x86_64 when try to build (play) the React Native app with Xcode for iOS.

Here I report the example of two apps, with two different versions of Realm and React Native, both with the same problem.

To solve, we need to:

cd ios
rm -rf Pods
pod install

This happens several times a day, we have not yet discovered the reason.

My guess is that this is related to branch exchange. However, when changing branches, neither React Native nor Realm versions are changed. (ios/Pods and node_modules are ignored on GIT)

React Native 0.62.2 and RealmJS 6.0.2

React Native 0.61.5 and RealmJS 3.6.5

Steps to Reproduce

Unfortunately, we still haven’t found a standard behavior.

As @somebody32 says here https://github.com/realm/realm-js/issues/3221#issuecomment-723875769

Looks like it is happening every time there is a change in Pods (ie adding a new or upgrading a version of any pod, not Realm). Realm is 10.0.1.

The temporal solution is to clean the build and do pod install again (no need to remove pods or node_modules folder), but I agree that it is pretty time consuming

Code Sample

Both projects are created using react-native init, without any customization in the metro, babel or cocoapods scripts.

Version of Realm and Tooling

• Realm JS SDK Version: 3.6.5 and 6.0.2
• React Native: RN 0.61.5 and 0.62.2 both with cocoapods and autolinking
• Cocoapods: 1.9.3
• Xcode: 11.7 (11E801a)
• Node: 12.16.3 with nvm
• Client OS & Version: macOS Catalina 10.15.6 (19G2021)
• Which debugger for React Native: None

Maybe related to https://github.com/realm/realm-js/issues/2271 https://github.com/realm/realm-cocoa/issues/2393

[somebody32]

Looks like it is happening every time there is a change in Pods (ie adding a new or upgrading a version of any pod, not Realm). Realm is 10.0.1.

The temporal solution is to clean the build and do pod install again (no need to remove pods or node_modules folder), but I agree that it is pretty time consuming

[kneth]

You can add something like

post_install do |installer|
  installer.pods_project.build_configurations.each do |config|
    config.build_settings["EXCLUDED_ARCHS[sdk=iphonesimulator*]"] = "arm64"
  end
end

to your app’s pod. See also https://stackoverflow.com/questions/63607158/xcode-12-building-for-ios-simulator-but-linking-in-object-file-built-for-ios