If you received a “No Devices Registered” error message, please do the following:
Connect your iDevice
On Xcode, make sure that your device is selected instead of iPhone Simulator
Click on “Fix Issue”
iReSign is an awesome application and because it is not available on the AppStore, Apple requires that you go through an extra step to enable the application.
Open System Preferences
Click on Security & Privacy
Click on Open on the dialog window that opens up.
Click on the General tab
Click on Open Anyways towards the bottom. Be sure that the application says iReSign and not something else.
If the app fails to install your iDevice, the most commonly reason is because the device’s UUID is not associated with the mobileprovision. Please connect the iDevice to your computer, select it on Xcode, and click on “Fix Issue“. Copy the new profile to your desktop and resign the ipa using iReSign.
Unlike iOS 8 which had a continue button for the ‘Untrusted Developer‘ screen, iOS 9 simply has a cancel.
Not the end of the world and a very easy fix
Click on Verify App.
Please note that it may take a minute or two for the app to ‘verified’ and in some cases, you may have to go click on < Profile and then your Apple ID again to see if the status changed to Verified.
Click on Settings
Click on General
Click on Profile
Under Developer App, click on the entry that pertains to your Apple ID
Click on Trust “<your developer id>”