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
================================

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)
It has been a while since this question has had love, but it seems it's not fully resolved. I'm going to add what I've found.

Here's the way I ran my test. We're just getting the first release of our app developed and don't have a release on the app store. So what I did was I took a bundle Id from another app I have on the app store, put it in my new app in Xcode 8.3, and tested this update functionality. I'm interested in the question of: Can app A update itself using the `SKStoreProductViewController`?

1) iOS 10.3 on iPhone. I've run the test and it works in the 6 or so trials I've made. What happens is that when I do the install from within `SKStoreProductViewController`, it crashes my app (not surprising-- I'm installing over the "same" app-- an app with the same bundle Id), but the install proceeds. You see the regular download progress indicator you normally see for an app download from the app store.

2) iOS 11 on an iPad (iOS11, beta 5, I believe-- the build number is 15A5341f). When attempting the update (update app A from within app A), using `SKStoreProductViewController`, this did not work. I get the following alert after pressing on the "update" button. I've tried this several times. The app doesn't crash. It just doesn't download the "update". I'm not sure if this is typical of beta versions of iOS, or is a change in the `SKStoreProductViewController` behavior.

[![Failed app update](https://i.stack.imgur.com/x9jCD.png)](https://i.stack.imgur.com/x9jCD.png)

3) iOS 11, same device: But tried to update app B from within app A. I ran this test to see if the problem was that I just couldn't do download at all within `SKStoreProductViewController` in a beta version. This worked. I was able to do the download in this case. 

I'll try to report back in on a test once iOS 11 is released-- to see if my test 2) then works or stays the same.