Allow access of application based on ip, or proxy network coverage

I have a reader application and we are customizing the reader to a certain institution to allow the user to use the application and read from its content. I have to verify whether he is under a certain proxy coverage and that he is logged in to that proxy.

I personally have very little experience with networking and proxy, therefore I would like to ask, whether this is doable and if so, what is the best way to approach it?

In case this is doable will Apple accept it and how can Apple team test the functionality?

I have come over this solution, but I'm not sure if this is what I need: How can I get the username for a proxy host from KeyChain?

Your guidance would be much appreciated.

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