Question

Is it theoretically possible to use in-app purchases to update an iOS app automatically? Basically, using StoreKit to replace existing code on the device? The IAP itself would be free so that the user doesn’t need to be involved.

In general terms, how would one go about implementing such a system?

I don’t have need of this, I just thought it would be interesting.

Answer 1

In-app purchase as the name implied, is for purchase only, no free in-app purchases are allowed.

Also, you’re not allowed to not download or install executable code.

3.3.2 An Internal Use 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.

So I don’t think what you’re thinking is not really possible.