1. flutter config --enable-swift-package-manager
2. flutter create my_app && cd my_app
3. flutter pub add image_picker_ios:0.8.13+2
4. flutter build ios --config-only
5. open ios/Runner.xcworkspace
6. Build app in Xcode
7. flutter pub add image_picker_ios:0.8.13+6
8. Build app in Xcode

This will cause an error. Looks like it's still using image_picker_ios:0.8.13+2, despite the symlink being updated to image_picker_ios:0.8.13+6

In file included from /path/to/.pub-cache/hosted/pub.dev/image_picker_ios-0.8.13+2/ios/image_picker_ios/Sources/image_picker_ios/FLTImagePickerPlugin.m:15:
/path/to/.pub-cache/hosted/pub.dev/image_picker_ios-0.8.13+2/ios/image_picker_ios/Sources/image_picker_ios/./include/image_picker_ios/messages.g.h:16:29: error: redefinition of 'FLTSourceCamera'
   16 | typedef NS_ENUM(NSUInteger, FLTSourceCamera) {
      |                             ^

So far the only way I can figure out how to fix it, is to hard close Xcode.