Implement :data:firestore-impl for iOS

[kikuchy]

Kind (Required)

• Proposal / Discussion

Overview (Required)

• In order to achieve Kotlin Multiplatform API implementation #136, we should make iOS implementation (as Kotlin/Native module) of :data:firestore instead of :data:firestore-impl .
• Or make :data:firestore-impl Kotlin Multiplatform module.
• Using Cocoapods's package to Kotlin Multiplatform module is hard currently, so we need in-memory or saving local file system firestore stub.
  • If you know how to use Cocoapods's package to Kotlin mpp, please realize!
  • It looks like Firebase modules in Carthage is experimental status. If you can use it, please do that! (Maybe we can use Frameworks of Carthage via cinterop feature of Kotlin/Native. But I haven't try it.)

Links

• https://github.com/firebase/firebase-ios-sdk/blob/master/Carthage.md