Similar to Android's Play Store Key, Apple has a rather arcane, but well-defined, process of generating keys and signing its .ipa packages to deploy to your iOS devices for testing. In the end, what you're using should look something like this with nice "Valid" sections everywhere, for both a development signing Provisioning Profile, and Certificate, as well as various Ad-hoc or other production profile/certificate combinations:
Links for all of Apple's steps for this are listed here, since Epic does not link them directly as it does for Android. Note, you'll need a valid Developer Account with Apple for most of these links.
- First, you will need an AppID, make sure that if you use something such as "com.mastering.*" that in your project settings you don't set it to "com.mastering" or this will not be found, it needs to be "com.mastering.dev" or something for the provisioning profile to match your certificate (more on that from Apple in a moment): https://developer.apple.com/account/ios/identifier/bundle
- Set up at least one device (such as test iPads or iPhones): https://developer.apple.com/account/ios/device/ipad
- You will need to get familiar with making a development (you only get one of these) and Ad-hoc/Store distribution certificates. It's recommended to get started with the development certificate if this is your first time going through the process with an Apple build: https://developer.apple.com/account/ios/certificate/create
- And then similarly, you'll want to get accustomed to making Provisioning Profiles – both a single development one for your team typically, and then one or more for Ad-hoc/Store distribution again: https://developer.apple.com/account/ios/profile/
Download these from the links by clicking on them, and import them into UE4. Hopefully all goes well, but for what it's worth, in years of development, I have never seen someone go through this process and have it succeed on the first try. Fortunately, there are thousands of others out there who have probably hit the same snags you will, and after a bit of searching, solutions can typically be found online for whatever issues stop you from having a smooth, successful setup here.