RxSwift 4.4 can't be integrated as Cocoapods static library due to RxAtomic dependency

[robmaceachern]

Short description of the issue:

Cocoapods (1.6.0.beta.2) can't integrate RxSwift 4.4 as a static library without workarounds. RxSwift 4.3 doesn't have this problem. Sample Podfile:

platform :ios, '11.0'

target 'Project' do
  pod 'RxSwift', '~> 4.4'
end

Expected outcome:

pod install succeeds: Pod installation complete!

What actually happens:

pod install fails:

[!] The following Swift pods cannot yet be integrated as static libraries:

The Swift pod `RxSwift` depends upon `RxAtomic`, which do not define modules. To opt into those targets generating module maps (which is necessary to import them from Swift when building as static libraries), you may set `use_modular_headers!` globally in your Podfile, or specify `:modular_headers => true` for particular dependencies.

Workarounds

1. Add use_modular_headers! to the Podfile. This allows the integration to succeed but it applies to all pods in the Podfile (I'm not sure what side-effects this could potentially have).
2. Add pod 'RxAtomic', '~> 4.0', :modular_headers => true to the Podfile. Allows integration to succeed. Not sure about the side-effects but should be safer than use_modular_headers!.

RxSwift/RxCocoa/RxBlocking/RxTest version/commit

4.4

Platform/Environment

• [x] iOS
• [ ] macOS
• [ ] tvOS
• [ ] watchOS
• [ ] playgrounds

How easy is to reproduce? (chances of successful reproduce after running the self contained code)

• [x] easy, 100% repro
• [ ] sometimes, 10%-100%
• [ ] hard, 2% - 10%
• [ ] extremely hard, %0 - 2%

Xcode version:

10.1

Installation method:

• [x] CocoaPods
• [ ] Carthage
• [ ] Git submodules

I have multiple versions of Xcode installed:
(so we can know if this is a potential cause of your issue)

• [x] yes (9.4.1, 10.0, 10.1)
• [ ] no

Level of RxSwift knowledge:
(this is so we can understand your level of knowledge
and formulate the response in an appropriate manner)

• [ ] just starting
• [x] I have a small code base
• [ ] I have a significant code base

[kzaher]

Hi @robmaceachern ,

The workarounds you've suggested are only workarounds for Podfile. Any idea what should we do to add proper support? PR?

[radex]

I have the same issue, but the workarounds are not working for me. My Podfile setup is… well… pretty complicated:

def common
  pod 'RxSwift',                '~> 4.0', inhibit_warnings: true
  pod 'RxCocoa',                '~> 4.0'
  pod 'RxAtomic',               '~> 4.0', :modular_headers => true
  # other pods…
end

abstract_target 'CommonIOS' do
  platform :ios, '11.2'
  use_frameworks!

  common

  target 'iOS' do
    # other pods
  end

  target 'NozbeKit' # <- this is a framework included by main app and also app extensions of the same app
  # … app extensions
end

target 'WatchApp' do
  platform :watchos, '3.0'
  use_frameworks!

  common
end

(I don't have a solution to offer, but I thought I'll post this so that a nested frameworks case is taken into account in the discussion :) )

[kzaher]

Ok, but does anyone know what do we need to add to our RxAtomic podfile to support this properly?

[robmaceachern]

I’m not very familiar with the details of this but it looks like what is required is setting DEFINES_MODULE in the podspec config settings. From the Cocoapods 1.5 release notes:

... you will be able to opt into stricter header search paths (and module map generation for Objective-C pods). As a pod author, you can add 'DEFINES_MODULE' => 'YES' to your pod_target_xcconfig.

So something like this to RxAtomic.podspec might work:

s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES' }

I don't have time for a PR at the moment but if some free time opens up I can give it a try.

Possibly useful info:
ios - Is there any downside to setting DEFINES_MODULE = YES in my podspec? - Stack Overflow

[kzaher]

As far as I can tell adding use_modular_headers! to top of Podfile works.

Adding s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES' } to RxAtomic.podspec doesn't work as far as I can tell. (Cocoapods 1.6.0-beta.2)

Does anybody have any more information?

[kzaher]

There was caching issue.