Apple has been fine with WebViews in apps since the beginning of the App Store, including WebViews that make calls to native code, like in the Quip app. WKWebView even has APIs for native and web code to communicate. It's OK for a WebView to call out to your native code that saves data to disk, registers for push notifications, plays a sound, and so on.
React Native is very much like a WebView except it calls out to one more native API (UIKit) for views and animations instead of using HTML.
What neither WebViews nor React Native do is expose the ability to dynamically call any native method at runtime. You write regular Objective-C methods that are statically analyzed by Xcode and Apple and it's no easier to call unauthorized, private APIs.
With Expo all of the native modules are safe to use and don't expose arbitrary access to native APIs. Apps made with Expo are set up to be good citizens in the React Native and Apple ecosystems.
Well, let's be clear here. I use React Native, and it would take me about 30m to write a bridged React Native method that could execute ObjC code dynamically, including accessing all the private APIs you could want.
Yeah. Objective-C is definitely really flexible. From my reading of the warning, the important thing is not to execute Objective-C dynamically or access private APIs regardless of whether you're using React Native, Cordova, a WebView, or even a bare iOS app.
Simple: JIT compilers are banned and so that excludes any modern browser's JavaScript implementation from iOS. But anyone using Apple's JavaScriptCore has nothing to fear.
The rules explicitly forbid any HTML renderer or JS interpreter aside from WebKit, JIT or no JIT. I believe all the popular third party browsers today still use the non-JIT UIWebView rather than WKWebView because the former gives you more control over the request cycle
WKWebView has JIT. In executes the JS in a different process than the hosted app; there the JIT lives, this special process is whitelisted to do JIT magic.
React Native is very much like a WebView except it calls out to one more native API (UIKit) for views and animations instead of using HTML.
What neither WebViews nor React Native do is expose the ability to dynamically call any native method at runtime. You write regular Objective-C methods that are statically analyzed by Xcode and Apple and it's no easier to call unauthorized, private APIs.
With Expo all of the native modules are safe to use and don't expose arbitrary access to native APIs. Apps made with Expo are set up to be good citizens in the React Native and Apple ecosystems.