[wip] Native Swift SDK

[jbrower95]

Native iOS SDK

Changelog:

• Exposes a new, Swift 5.5 future-based Native iOS SDK for Waas.
• Rebases the existing Waas react-native package on top of this.

Layout

ios/swift - The code-home of WaasSdk.podspec, the native iOS sdk. ios/react-native - The wrapper library for RN.

Architecture

1. waas-sdk-react-native (whose name is set to look like a JS package probably), depends on WaasSdk (the native iOS waas pod).
2. The class names between the two pods are duplicative, for convenience of the reader.
3. WaasSdk.* uses Combine and Swift futures to perform async operations with the cross-platform Go SDK.
4. The react-native SDK then rewraps these swift futures using the Operation.swift "bridge" method -- this awaits the future, and passes on either a resolution or rejection to React Native.

Usage

See README.md, but users can directly depend on WaasSdk.podspec from the root of this repo, which will pull in the code from ios/swift. Setup instructions are included.

Testing

• Tested all example app scenarios via react-native, all working.

Notes / Feedback on M1 setup

• WaasSdkGo.xcframework didn't work out of the box. Had to remove the x86 simulator binaries for the app to build. We should be able to address this by building the multi-arch binary using lipo in a different way.
• SSL install also didn't work out-of-the-box, which lead to me using brew install openssl@1.1, and changing my header search paths. May have been something with my machine, but potentially a solution worth noting in the README.
• Building with flipper takes forever, especially on a bad connection. Probably good to tell folks that they should build the sample app with NO_FLIPPER=1 pod install (we can maybe change the yarn script for this)

[jbrower95]

Will push a commit with a sample app, and some more internal changes to the framework to make swift development easier.