Question: Couldn't find any information regarding this... if I launch a `SKStoreProductViewController` instance from within my app, feeding it the iTunes URL of that app, does it allow for app updates? In other words I'd like to have an "Update" button within my app that shows a `SKStoreProductViewController` and allows the user to update the app from there.

This is hard to verify as `SKStoreProductViewController` is running a "sandboxed" version of the App Store, and that I'm not sure what determines whether it shows the "Open" or "Update" button.

Answer: 
I can verify that update does in fact show when presenting an owned app, that is installed that also has an update.

It of course also shows "Install" for apps you own but don't have installed and "Open" for apps installed and up to date.

*This is using production code in a shipped app though I still couldn't find any verification in Apple's docs.*

Updating the current app through
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If you are trying to Update The currently open app in an `SKStoreProductViewController`, it will throw an error on later versions of iOS as unable to install. Instead you should open the app store URL to force the App Store to open. `itms-apps://itunes.apple.com/app/apple-store/id375380948?mt=8`

![enter image description here](https://i.stack.imgur.com/MuEVO.png)
Interestingly, I tried the same for my own app, where I tried to show my app's ID inside the SKStoreProductViewController, by detecting an earlier version of the app. 
The screen was visible, the update button was there, HOWEVER, clicking on update, and still remaining in the app's context made SKStore throw an error "Cannot download at this time".
However, I haven't tried immediately exiting the app after clicking on update should work

Its probably because an app must be exited before an update can be performed?