Friction adding swift plugin to objective-c project

[xster]

flutter create a non-swift project

In pubspec.yaml, add a swift plugin such as flutter_iap.

1. flutter run warns about use_frameworks! from pod install. Easy to resolve so far.
2. Building gives The “Swift Language Version” (SWIFT_VERSION) build setting must be set to a supported value for targets which use Swift. This setting can be set in the build settings editor. error.
   Seems like swift pod developers need to specify
   s.pod_target_xcconfig = { 'SWIFT_VERSION' => <a version above 2.3 for it to work with Xcode 9> }
   in their podspec. Added temporary hack in Podfile with

post_install do |installer|
  installer.pods_project.targets.each do |target|
    target.build_configurations.each do |config|
      config.build_settings['SWIFT_VERSION'] = '3.2'
    end
  end
end

and re-pod install
3.

#import "Headers/flutter_iap-umbrella.h"
            ^
   .../ios/Pods/Target Support Files/flutter_iap/flutter_iap-umbrella.h:13:9: error: include of non-modular header inside framework module 'flutter_iap': '.../.pub-cache/hosted/pub.dartlang.org/flutter_iap-1.0.1/ios/Classes/FlutterIapPlugin.h'

Add

pre_install do |installer|
  # workaround for https://github.com/CocoaPods/CocoaPods/issues/3289
  Pod::Installer::Xcode::TargetValidator.send(:define_method, :verify_no_static_framework_transitive_dependencies) {}
end

and

post_install do |installer|
  installer.pods_project.targets.each do |target|
    # workaround for https://github.com/CocoaPods/CocoaPods/issues/7463
    target.headers_build_phase.files.each do |file|
      file.settings = { 'ATTRIBUTES' => ['Public'] }
    end
  end
end

to make it work.

Wonder if we can add some automatic handling of swift plugins in the default objective-c project's Podfile

[xster]

cc @mravn-google

[pinkfish]

I tried these work arounds and it is still failing to build with the same error. Do I need to make any specific changes to the podfile that is being included or something too? I just did these in my app podfiles...

 <module-includes>:1:9: note: in file included from <module-includes>:1:
    #import "Headers/flutter_places_dialog-umbrella.h"
            ^
    /Users/ddb/git/mobile/flutter_fuse/ios/Pods/Target Support Files/flutter_places_dialog/flutter_places_dialog-umbrella.h:13:9: error: include of non-modular header inside framework module 'flutter_places_dialog': '/Users/ddb/git/flutter_places_dialog/ios/Classes/FlutterPlacesDialogPlugin.h'
    #import "FlutterPlacesDialogPlugin.h"

[dlutton]

@pinkfish
Are you using cocoapods 1.5.0?

If so, try downgrading to 1.4.0. That's the only way I've been able to get it to work.
sudo gem install cocoapods -v 1.4.0
delete your Podfile.lock and Podfile dir in /ios and do a pod install

[mravn-google]

@dlutton @pinkfish We have been unable to make Cocoapods 1.4.0 work all the way through to app store archives, and we'll be supporting only Cocoapods 1.5.0 or later going forward.

With Cocoapods 1.5.0 and newest Flutter tooling (on master), all you should have to do is patch your Podfile as follows:

target 'Runner' do
  use_frameworks! # <--- add this
  ...
end

post_install do |installer|
  installer.pods_project.targets.each do |target|
    target.build_configurations.each do |config|
      config.build_settings['ENABLE_BITCODE'] = 'NO'
      config.build_settings['SWIFT_VERSION'] = '3.2' # <--- add this
    end
  end
end

Then delete ios/Podfile.lock and execute flutter run.

Filing issue that changing ios/Podfile does not cause flutter run to redo pod install #16734

[dlutton]

@mravn-google Tried cocoapods 1.5.0 and it's failing with:

Xcode's output:
↳
    === BUILD TARGET Runner OF PROJECT Runner WITH CONFIGURATION Debug ===
    ld: warning: Auto-Linking library not found for -lswiftSwiftOnoneSupport
    ld: warning: Auto-Linking library not found for -lswiftCoreAudio
    ld: warning: Auto-Linking library not found for -lswiftCore
    ld: warning: Auto-Linking library not found for -lswiftQuartzCore
    ld: warning: Auto-Linking library not found for -lswiftCoreImage
    ld: warning: Auto-Linking library not found for -lswiftCoreGraphics
    ld: warning: Auto-Linking library not found for -lswiftAVFoundation
    ld: warning: Auto-Linking library not found for -lswiftCoreMedia
    ld: warning: Auto-Linking library not found for -lswiftDispatch
    ld: warning: Auto-Linking library not found for -lswiftObjectiveC
    ld: warning: Auto-Linking library not found for -lswiftCoreFoundation
    ld: warning: Auto-Linking library not found for -lswiftUIKit
    ld: warning: Auto-Linking library not found for -lswiftDarwin
    ld: warning: Auto-Linking library not found for -lswiftMetal
    ld: warning: Auto-Linking library not found for -lswiftsimd
    ld: warning: Auto-Linking library not found for -lswiftFoundation
    Undefined symbols for architecture x86_64:

[✓] Flutter (Channel master, v0.3.1-pre.35, on Mac OS X 10.13.3 17D102, locale en-US)
    • Flutter version 0.3.1-pre.35 at /Users/dlutton/development/flutter
    • Framework revision 7b163c7c0b (4 hours ago), 2018-04-18 20:31:45 -0700
    • Engine revision 3cc8d82895
    • Dart version 2.0.0-dev.48.0.flutter-fe606f890b

[✓] iOS toolchain - develop for iOS devices (Xcode 9.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 9.3, Build version 9E145
    • ios-deploy 1.9.2
    • CocoaPods version 1.5.0

[mravn-google]

@dlutton Would you be able to share your pubspec.yaml and ios/Podfile?

[dlutton]

@mravn-google
Maybe it's my flutter_tts plugin I wrote in swift that's failing. It worked with cocoapods 1.4.

Podfile:

# Uncomment this line to define a global platform for your project
# platform :ios, '9.0'

# CocoaPods analytics sends network stats synchronously affecting flutter build latency.
ENV['COCOAPODS_DISABLE_STATS'] = 'true'

def parse_KV_file(file, separator='=')
  file_abs_path = File.expand_path(file)
  if !File.exists? file_abs_path
    return [];
  end
  pods_ary = []
  skip_line_start_symbols = ["#", "/"]
  File.foreach(file_abs_path) { |line|
      next if skip_line_start_symbols.any? { |symbol| line =~ /^\s*#{symbol}/ }
      plugin = line.split(pattern=separator)
      if plugin.length == 2
        podname = plugin[0].strip()
        path = plugin[1].strip()
        podpath = File.expand_path("#{path}", file_abs_path)
        pods_ary.push({:name => podname, :path => podpath});
      else
        puts "Invalid plugin specification: #{line}"
      end
  }
  return pods_ary
end

target 'Runner' do
  use_frameworks!

  # Prepare symlinks folder. We use symlinks to avoid having Podfile.lock
  # referring to absolute paths on developers' machines.
  system('rm -rf Pods/.symlinks')
  system('mkdir -p Pods/.symlinks/plugins')

  # Flutter Pods
  generated_xcode_build_settings = parse_KV_file('./Flutter/Generated.xcconfig')
  if generated_xcode_build_settings.empty?
    puts "Generated.xcconfig must exist. If you're running pod install manually, make sure flutter packages get is executed first."
  end
  generated_xcode_build_settings.map { |p|
    if p[:name] == 'FLUTTER_FRAMEWORK_DIR'
      symlink = File.join('Pods', '.symlinks', 'flutter')
      File.symlink(File.dirname(p[:path]), symlink)
      pod 'Flutter', :path => File.join(symlink, File.basename(p[:path]))
    end
  }

  # Plugin Pods
  plugin_pods = parse_KV_file('../.flutter-plugins')
  plugin_pods.map { |p|
    symlink = File.join('Pods', '.symlinks', 'plugins', p[:name])
    File.symlink(p[:path], symlink)
    pod p[:name], :path => File.join(symlink, 'ios')
  }
end

post_install do |installer|
  installer.pods_project.targets.each do |target|
    target.build_configurations.each do |config|
      config.build_settings['ENABLE_BITCODE'] = 'NO'
      config.build_settings['SWIFT_VERSION'] = '3.2'
    end
  end
end

pubspec.yaml

name: fof
description: A new Flutter project.

dependencies:
  flutter:
    sdk: flutter
  connectivity:
  flutter_tts:
  share: "^0.3.1"

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^0.1.0

dev_dependencies:
  flutter_test:
    sdk: flutter


# For information on the generic Dart part of this file, see the
# following page: https://www.dartlang.org/tools/pub/pubspec

# The following section is specific to Flutter.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  assets:
    - assets/failure.webp
    - assets/fortune.webp
    - assets/LaunchImage.png

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.io/assets-and-images/#resolution-aware.

  # For details regarding adding assets from package dependencies, see
  # https://flutter.io/assets-and-images/#from-packages

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  fonts:
    - family: Lato
      fonts:
        - asset: fonts/Lato-Regular.ttf
          weight: 400
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies, 
  # see https://flutter.io/custom-fonts/#from-packages

[mravn-google]

The flutter_tts plugin works fine when included in a Flutter project created using -i swift.

[mravn-google]

Adding an empty Swift file to your Flutter iOS project in Xcode and accepting to add bridging header also works.

[dlutton]

Okay I’ll try that out thank you

[dlutton]

@mravn-google I confirmed it's working with cocoapods 1.5.0. Thank you sir

[goodis0]

@mravn-google can you explain how to

Adding an empty Swift file to your Flutter iOS project in Xcode and accepting to add bridging header also works.

Where am I creating this file and what is a bridging header?

[lukepighetti]

@goodis0 Did you find an answer to this? Trying to add a pub package to a project I created with Flutter: New Project in Visual Studio Code and it's failing due to SWIFT_VERSION error being discussed.

[lukepighetti]

Can confirm that @mravn-google provided a simple and effective fix #16049 (comment)