Xcode 6 - How to pick signing certificate/provisioning profile for Ad-Hoc distribution?

I was facing same issue, resolved using command line "xcodebuild" tool script, which is preinstalled with Xcode 6 (didn't need to re-install Xcode 5).

http://www.thecave.com/2014/09/16/using-xcodebuild-to-export-a-ipa-from-an-archive/

Script in terminal:

xcodebuild -exportArchive -archivePath $projectname.xcarchive -exportPath $projectname -exportFormat ipa -exportProvisioningProfile 'Provisioning Profile Name'

I had a similar issue when submitting to The App Store. I created an archive, then clicked "submit" and Xcode wanted to automatically sign with the default "XC com.*" wildcard provisioning profile instead of the explicit profile that already had.

To fix this, I just re-generated the profile on the Apple Developer Portal:

1) Go to developer.apple.com and find the distribution provisioning profile you want to use.
2) Select it, click "Edit", re-name the profile, and click "Generate".
3) Download the provisioning profile to the Desktop and drag it onto the Xcode 6 icon.
4) Re-start Xcode 6.
5) Open the organizer window and click "Submit" on the archive you built. Xcode will automatically pick your explicit profile instead of the generic one.

Once you are in Organizer

• Select the ad-hoc build and click "Export...."
• Select "Save for Ad Hoc Deployment" -> Next
• Instead of selecting an organisation from the drop down select "Use local signing asset" -> Choose
• Export and save .ipa as before.

Of course you need to have generated, downloaded and installed the ad-hoc provisioning profile.