Basically, I want to do exactly what is already stated in this question – just in XCode 7.2.
The setup: I am developing an iOS app (using Ionic) for a client and they want to publish it to app store in their name under their account. They however don't want to give me their account login and details. I have received a distribution certificate and a provisioning profile in stead.
I have installed the .p12 distribution certificate and have received a .mobileprovision profile for App Store Distribution using this certificate. I am however completely unable to select this provisioning profile anywhere.
My only choice in the export of the archive happens when XCode asks me which developer account I want to archive with. And here I can only choose my own account (of course). That's obviously not what I want though.
"Once" (in XCode 5, according the linked question) I should have been able to select the external provisioning profile under "Code Signing", but this doesn't seem to exist anymore.
Can this be done without getting their account details? I know that I don't need to know their password, they can just export it to me. Right?
I don't think you can do exactly what you are saying without code signing it with their account (which you don't have access to). I see two possible solutions for you to achieve your goal:
Send them the Xcode project and explain to them how to sign in to Xcode, archive the app and send it up to the store
Upload the app to your personal store account and then transfer it to their account. See this link for details on how to do that: https://developer.apple.com/library/ios/documentation/LanguagesUtilities/Conceptual/iTunesConnect_Guide/Chapters/TransferringAndDeletingApps.html