Message from Apple Review...

Hello everyone,

I think you should know about this : https://9to5mac.com/2017/03/07/apple-cracks-down-on-hot-push-code-sdks/
So, If your app is live on store then you should contact to your SDK provider and ask for solution. They might contact to Apple Inc. and find some better support.

Have there been any reports of this affecting reactnative apps?

Does caused by [*** performSelector:NSSelectorFromString([NSString stringWithFormat:@"%@",@"********"])]?

we think we might have just been hit by this - we use a 3rd party lib that has react native in it + as far as we can tell is the most likely source of the issue

From the React Native github issues;

3.3.2 of Apple Developer Program License:

An Application may not download or install executable code. Interpreted
code may only be used in an Application if all scripts, code and interpreters are
packaged in the Application and not downloaded. The only exception to the
foregoing is scripts and code downloaded and run by Apple's built-in WebKit
framework or JavascriptCore, provided that such scripts and code do not change
the primary purpose of the Application by providing features or functionality that are
inconsistent with the intended and advertised purpose of the Application as
submitted to the App Store.

explicitly mentions that:

An Application may not download or install executable code

React Native does none of these. And so, using React Native doesn't expose you to the aforementioned issue.

method_exchangeImplementations() is the basis of method swizzling. It is used by every major library (AFNetworking, analytics, growth marketing, crash management sdks, growth automation) and many apps. Apps that have a valid use of method_exchangeImplementations() aren't affected.

I don't thing Apple is going to break this. Changing behavior of app using JavaScriptCore and executing javascript that is downloaded and executed is at risk of man in the middle attack.

If you look at the timing of this change, it points to CIA Wikileaks earlier that day... I believe on March 7

I am not a security expert, but I think Apple should allow javascript downloads over TLS / HTTPS, require Strict-Transport-Security header, use certificates to establish trust, and establish explicit trust between the app and the javascript source.

We have seen improvements when we moved "Beyond Deep Linking" to iOS Universal Links (and Android App Links), where, the website uses apple-app-site-association in the .well-known subfolder of website and the app has to add the applinks in the app capabilities section in Xcode.

What about react native apps that use a service like code push. With a service like that in theory you could completely change the app functionally. We use apps that use code push and while we don't ever change app functionality using code push, we have fixed a few critical bugs and pushed it immediately to clients. It's very concerning as to what exactly this could apply to.

Which SDK? Could you specify.

I don't know, that response sounds a little like whistling past the graveyard. While React Native may not have been intended for the same purpose as Rollout.io, it is certainly possible to use it that way.

In fact, it is one of the touted "benefits" of RN, as explicitly called out by some users. Note the quote from this blog post https://www.aerofs.com/blog/reactnativeautoupdater-dynamic-updates-to-react-native-apps/

"Technically, we can ship a React Native app with no Javascript code, and point it to a URL on the server on the internet. That would be just like how the dev environment works. The problem with that is that JS-bundles tend to be very big. A simple app can easily run into a couple of megabytes. Wasting the time and bandwidth to download them every time the app runs is clearly not an ideal way of doing things.

"Luckily, this is super easy to solve. We can ship the app with an initial JS-bundle, and check for updates in the background after the app starts."

I wouldn't be shocked to see RN come under scrutiny in the future (in fact, I'd go so far as to say is *should* come under scrutiny).

Skillz eSports SDK.

Outside of std ios frameworks we have a couple of ad providers (AdMob, Applovin) and facebook analytics. None of these seem very likely candidates. We definately dont do any of the 'failure' things in our main app code.

The frustrating part is there does not seem to be any way or any tools to actually determine which frameworks might be causing the issue - as far as we can tell the only way to find out is to build apps with each of the frameworks removed one at a time and see if Apple accept/reject whcih hardly seems intelligent..

>and see if Apple accept/reject whcih hardly seems intelligent..

This isn't a new situation. Apple tends to keep things vague so they can define/apply on the fly, without being boxed in/dragged into debate ("You didn't explicitly write that I couldn't do this, so get out of my way"), so I don't think there is a solution that favors everyone.

Of course, it leaves devs to poke around in the dark, at least until the dust settles, and some will find it more of a burden than others - welcome to the app store.

As far as we can tell React Native is the issue for us.

What is entirely possible is that the 'forbidden' methods exist within the RN library regardless of whether they get used or not (dont know how intelligent the linkers are for different langs these days). Simply by virtue of the methds existing in the library the app fails whatever testing tool is being used.

So the key is that 'its certainly possible to use it that way' even if no one ever does/did knowingly or otherwise.

Any one any clue as to who/what determines exactly what is considered as "significant changes to your app’s behavior".

As far as we can tell any change at all is considered "signficant".

We just had an app rejected twice based on a minimum functionailty reasoning, we removed Code-Push and the app was approved??