Cocoapods: APPLICATION_EXTENSION_API_ONLY is not set with Xcode 12 & CocoaPods 1.9.3

[pronebird]

• [x] I've read and understood the CONTRIBUTING guidelines and have done my best effort to follow.

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What did you do?

I have the following post install hook to make PureLayout work with extensions on iOS:

post_install do |installer|
  # NOTE: If you are using a CocoaPods version prior to 0.38, replace `pods_project` with `project` on the below line
  installer.pods_project.targets.each do |target|
    if target.name.end_with? "PureLayout"
      target.build_configurations.each do |build_configuration|
        if build_configuration.build_settings['APPLICATION_EXTENSION_API_ONLY'] == 'YES'
          build_configuration.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] = ['$(inherited)', 'PURELAYOUT_APP_EXTENSIONS=1']
        end
      end
    end
  end
end

But after updating to CocoaPods 1.9.3 & Xcode 12, the APPLICATION_EXTENSION_API_ONLY flag is never set leaving the build configuration broken for PureLayout when built against extensions.

What did you expect to happen?

ℹ Please replace these two lines with what you expected to happen.
e.g. Install all pod dependencies correctly.

What happened instead?

ℹ Please replace these two lines with of what happened instead.
e.g. Pod A is missing the subspec B for target C.

CocoaPods Environment

ℹ Please replace these two lines with the output of pod env.
e.g. via pod env | pbcopy

Project that demonstrates the issue

ℹ Please link to a project we can download that reproduces the issue.
You can delete this section if your issue is unrelated to build problems,
i.e. it's only an issue with CocoaPods the tool.

[dnkoutso]

Please upload a sample app demonstrating the issue.

[dnkoutso]

Its very hard for us to diagnose with the given error report.

[pronebird]

@dnkoutso it's not difficult to reproduce. Before CocoaPods 1.8 APPLICATION_EXTENSION_API_ONLY was set for widget extensions, it's not anymore. I had to downgrade to 1.7.5 to be able to build my project. I believe it's not difficult to set up a sample Xcode project with widget extension target and then just dump build_configuration.build_settings in post_install hook. The issue was raised on PureLayout repo too https://github.com/PureLayout/PureLayout/issues/245

[dnkoutso]

@pronebird hmm We did have this https://github.com/CocoaPods/CocoaPods/issues/9233 that says 1.9.0 release and then this https://github.com/CocoaPods/CocoaPods/pull/9693 which is for 1.10.0.

Have you tried 1.10.0.rc.1 by any chance?

[pronebird]

@dnkoutso yeah I saw that issue before & thought that it was fixed, but alas I couldn't build my Xcode project after updating from 1.5 -> 1.9.3. Then I downgraded to 1.8 - same issue, then 1.7.5 which worked. I haven't tried the 1.10 yet, but I can try it tomorrow morning.

[dnkoutso]

Thanks a lot for trying it out. I will try to find sometime myself to check out for prior versions.

[dnkoutso]

Please update here when you try 1.10 version.

[pronebird]

@dnkoutso so I have just installed the 1.10.0.rc.1:

$ bundle info cocoapods
  * cocoapods (1.10.0.rc.1)
    Summary: The Cocoa library package manager.
    Homepage: https://github.com/CocoaPods/CocoaPods
    Path: /Users/pronebird/.rvm/gems/ruby-2.6.5/gems/cocoapods-1.10.0.rc.1

$ pod --version
1.10.0.rc.1

$ pod install
Analyzing dependencies
Downloading dependencies
Generating Pods project
Integrating client project
Pod installation complete! There are 8 dependencies from the Podfile and 8 total pods installed.

Widget target has APPLICATION_EXTENSION_API_ONLY = YES as expected:

Pods project for the Today widget has APPLICATION_EXTENSION_API_ONLY = NO 😞

Switched back to 1.7.5:

[dnkoutso]

It will really help to get a small sample project here that reproduces.

[pronebird]

@dnkoutso Alright, here you go. I have copied a sample old-fashion widget project by Apple & added CocoaPods 1.10.0.rc.1 and PureLayout pod with no other changes to the source code of the sample app.

Git repo: https://github.com/pronebird/cocoapods-issue-10087

That's what I see on my end:

[dnkoutso]

Thank you so much! I will hopefully find time this week to take a look.

[igor-makarov]

I see what the problem is - the APPLICATION_EXTENSION_API_ONLY flag moved to the .xcconfig file, and is not in the .pbxproj as perviously.

@dnkoutso it seems like this issue is due to relying on an implementation detail of CocoaPods.

@pronebird - I've checked the uses of the PURELAYOUT_APP_EXTENSIONS flag in the referenced library and there's only one - for RTL checks. It looks like something that might be done much more portably by using an availability check:

if (@available(iOSApplicationExtension 10.0, *)) {
} else {
}

[pronebird]

@igor-makarov not sure at what point the APPLICATION_EXTENSION_API_ONLY is added to the .xcconfig. I can't see it. https://github.com/pronebird/cocoapods-issue-10087/search?q=APPLICATION_EXTENSION_API_ONLY&type=

[igor-makarov]

There it is - https://github.com/pronebird/cocoapods-issue-10087/blob/24a4636f2bd50739af3f7aa937a6c49f3b929910/Pods/Target%20Support%20Files/PureLayout/PureLayout.debug.xcconfig#L1

[dnkoutso]

So sorry, is this still an issue?

I do not quite understand this:

@dnkoutso it seems like this issue is due to relying on an implementation detail of CocoaPods.

[igor-makarov]

The PureLayout developers are recommending a post_install hook that's no longer working because some implementation detail in project configuration has moved from .pbxproj to .xcconfig.

I have advised them how to resolve this in a more portable way on their end.

I think we can close this, what do you think?

[dnkoutso]

Ah, @pronebird wdyt? I think we can close this yes.

[pronebird]

@dnkoutso I suppose this can be fixed with the proper use of @available as outlined by @igor-makarov.

[dnkoutso]

Sounds good!