Allow library podspec to declare Swift Package Manager dependencies

[mfazekas]

Summary:

React-Native uses Cocapods for native dependency management on iOS. While CocoaPods is flexible and popular, Apple's Swift Package Manager is the new standard. Currently consuming packages available only via Swift Package Manager is not possible. This change implements a single extension so .podspec files can declare Swift Package Manager dependencies via

spm_dependency(s,  
     url: 'https://github.com/apple/swift-atomics.git', 
     requirement: {kind: 'upToNextMajorVersion', minimumVersion: '1.1.0'}, 
     products: ['Atomics'] 
   ) 

Changelog:

[IOS] [ADDED] - libraries can now declare Swift Package Manager dependencies in their .podspec with spm_dependency

Test Plan:

https://github.com/mfazekas/rn-spm-rfc-poc/

Is a simple demo for the feature:

1. Podspec declare dependency with:

   if defined?(:spm_dependency)
     spm_dependency(s,  
       url: 'https://github.com/apple/swift-atomics.git', 
       requirement: {kind: 'upToNextMajorVersion', minimumVersion: '1.1.0'}, 
       products: ['Atomics'] 
     ) 
   else 
     raise "Please upgrade React Native to >=0.75.0 to use SPM dependencies." 
   end 

2. import Atomics and ManagedAtomic is used in the code

3.) spm_dependency causes the dependency to be added via post_install hook in the workspace

4.) spm_dependecy causes the library to be linked with Atomics library

Limitations: #

1.) Some package target types will work with only some USE_FRAMEWORKS settings:

RN Linking	Static lib(eg Alamofire static)	Dynamic lib(eg Alamofire)	Macros
pod install.(default)	duplicate symbols 2️⃣	undefined symbols 3️⃣	✅ 1️⃣
USE_FRAMEWORKS=static pod install	duplicate symbols2️⃣	undefined symbols 3️⃣	✅1️⃣
USE_FRAMEWORKS=dynamic pod install	✅	✅	✅

1️⃣: more complex swift macros usually have runtime component - limitation might apply, as table above will apply
2️⃣: caused by a Xcode linking issue ObjC flag - duplicate link issue
3️⃣: can be fixed by linking the library to the app itself

2.) .xcworkspace needs to be reopened after pod install - this seems to be an Xcode bug and fixed in Xcode 16 beta.

See also:

react-native-community/discussions-and-proposals#587 (comment)
react-native-community/discussions-and-proposals#787

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[cipolleschi]

Thanks for the amazing PR. 👏
I left some comments in the code to simplify it a little bit and to make it easier to use.

I also have a couple of questions:

1.) only works USE_FRAMEWORKS=dynamic pod install

Does it works with static frameworks?

2.) .xcworkspace needs to be reopened after pod install - this could be worked around by not removing/readding spm dependencies

Do you think there is a way to detect whether dependencies changed so that we can emit a red message to prompt the user to close and reopen the .xcworkspace project?
Alternatively, we can kill Xcode, but if a person has multiple project open, that could be annoying.

[cipolleschi]

To simplify the usage for 3rd party dependencies, I'd properly move this function from the utils.rb directly to the react_native_pods.
In this way, instead of the check:

if const_defined?(:ReactNativePodsUtils) && ReactNativePodsUtils.respond_to?(:spm_dependency) 
  ReactNativePodsUtils.spm_dependency(s,  
    url: 'https://github.com/apple/swift-atomics.git', 
    requirement: {kind: 'upToNextMajorVersion', minimumVersion: '1.1.0'}, 
    products: ['Atomics'] 
  ) 
else 
  raise "Please upgrade React Native to >=0.75.0 to use SPM dependencies." 
end 

they can just:

if defined?(:spm_dependency)
  spm_dependency(s,  
    url: 'https://github.com/apple/swift-atomics.git', 
    requirement: {kind: 'upToNextMajorVersion', minimumVersion: '1.1.0'}, 
    products: ['Atomics'] 
  )
else 
  raise "Please upgrade React Native to >=0.75.0 to use SPM dependencies." 
end 

I would also consider backporting this to all the RN versions in the supported window (right now: 0.72, 0.73, 0.74) so that they don't even need to if-else.

What do you think?

[mfazekas]

Added as spm_dependency.

As noted #44627 (comment) this approach does depend on what linking (static/dynamic) the RN framework uses and what linking does the SPM product uses. This is something to consider with backporting, as it might require some further changes to be usefull in all scenarios

[mfazekas]

Thanks for the amazing PR. 👏 I left some comments in the code to simplify it a little bit and to make it easier to use.

I also have a couple of questions:

1.) only works USE_FRAMEWORKS=dynamic pod install

Does it works with static frameworks?

It's a bit complicated. I've tested with Alamofire Swift Package Manager package that has a dynamic and static product.

	Alamofire - static	AlamofireDynamic
USE_FRAMEWORKS=dynamic pod install	works	works
USE_FRAMEWORKS=static pod install	duplicate symbols	undefined symbol*
pod install	duplicate symbols	undefined symbol*

Now undefined symbols can be fixed by adding AlmofireDynamic to the user project. But modifying the user project is less than ideal as unlike Pods project which get regenerated with each pod install, the user project is not regenerated.

2.) .xcworkspace needs to be reopened after pod install - this could be worked around by not removing/readding spm dependencies

Do you think there is a way to detect whether dependencies changed so that we can emit a red message to prompt the user to close and reopen the .xcworkspace project? Alternatively, we can kill Xcode, but if a person has multiple project open, that could be annoying.

According to testing in Xcode 15.4, if there is a single swift package manager dependency, the regenerating the project might loose the dependency in the UI. (Not 100% reproducible)

spm-reload.mov

We can write an osascript that reloads the project if it's open, but it's a bit hacky

#!/usr/bin/osascript -l JavaScript

function main() {
  const app = Application("Xcode")
  const active = app.activeWorkspaceDocument();

  console.log("Active", app.activeWorkspaceDocument().file());

  const worspacePath = "/Users/boga/Work/OSS/react-native-sim/rn-spm-rfc-poc/example/ios/RnSpmRfcPocExample.xcworkspace"

  if (app.activeWorkspaceDocument().file() == filePath) {
	  app.activeWorkspaceDocument().close();
	  app.open(filePath);
  } 
}

main()

[cipolleschi]

Sorry for the late reply. I'm still catching up after the conferences of the past weeks.

One thing we can add is a big warning message that runs only if SPM dependencies are found.
The message can

• ask the user to close and reopen the XCWorkspace
• ask the user to run with dynamic frameworks (if it has not done that)

What do you think?

[mfazekas]

One thing we can add is a big warning message that runs only if SPM dependencies are found. The message can

• ask the user to close and reopen the XCWorkspace

I've tested this with new Xcode 16.0 beta and close/reopen issue is solved there. So likely some warning that

If you're using Xcode 15 or earlier you might need to reload the Xcode workspace

• ask the user to run with dynamic frameworks (if it has not done that)

The SPM might be a simple Swift Macro and in that case it works with all linking. If it's a static library then static linking causes link errors with duplicate symbols. If it's a dyanamic library, then static linking only works if the app also links with the dynamic library, otherwise they'll see undefined symbols.

So not sure what's the good message here.

Warning: Pod Foo using swift package Bar with static linking, this might cause linker errors. Consider using USE_FRAMEWORKS=dynamic, see https://github.com/facebook/react-native/pull/44627 for more information

Maybe we also add a url to this issue, or a new one created just for explaining the potential issues with SPM regarding linking?

What do you think?

Yes given that the reload issue seems to get's solved by new Xcode version, it don't think it's worth to mess with osascript workaround, so message is good there. The linking part is a bit complicated, not sure what's a good message there.

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@cipolleschi has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@cipolleschi merged this pull request in f903f34.

[github-actions]

This pull request was successfully merged by @mfazekas in f903f34.

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[ospfranco]

Hi! I'm trying to use a NPM dependency. Everything seems to be working until I open my project in Xcode. Then, I cannot open the Pods target. I only get this error.

Edit: Got an answer from Riccardo. One needs to use dynamic frameworks to make this feature work.