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iOS testing: TestFlight or Resigner

Michael Ebako-Hodgson


To seamlessly provide testers with access to your iOS app, we give you two options: Apple’s TestFlight, or our Resigner. This guide will help you to make an informed decision on which approach to take.

TestFlight is Apple’s platform for over-the-air installation and testing of mobile apps within the iOS Developer Program. Our Resigner is a code-signer built into the test IO platform through which you upload your iOS build directly for distribution.


The fastest way to test an app with test IO is through our built-in resigner. Simply upload a .IPA build file to the test IO platform during test setup. Our resigner will automatically detect if your app is already signed with an enterprise certificate and will provide the original build to our testers. If your app is not signed with an enterprise certificate, we will deliver the app under our certificate so that testers are able to access it.

There are a few technical limitations with using a resigner (our list can be found here). If your app includes in-app purchases, these features might get lost if the app is signed with a local certificate. It's not always obvious if there is something in your app that is unsupported. This is why it is important to work closely with your CSM to gain an understanding of this process. 


If your organization is already using TestFlight to manage builds, you likely already have a workflow (via Xcode) for distributing apps internally. Testing via TestFlight with the crowd is simple - create a TestFlight Public Link from the build you want to distribute - and add this as the environment to your new test cycle. Test IO will allow this functionality natively from our platform in 2020.

It is worth noting that TestFlight has some limitations. Using TestFlight means the app needs to go through Apple’s review process, which can last from 2 to 48 hours. And, since TestFlight distribution is not controlled by test IO, additional effort must be put into build management to avoid mid-test build updates as well as pre/post test cycle access to individual builds.


Ultimately, there is no “right” option. Using our resigner can help you get your tests running without having to wait for Apple’s approval: advantage, speed. However, if you already use TestFlight to manage builds and it ain’t broke, don’t fix it.



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