Apple has announced that developers can now invite up to 1,000 testers to beta test iOS apps by sending them an email invitation through iTunes Connect. Once the individual has accepted the invitation, testers can install the beta app on their iOS devices, get updated builds, and provide feedback, all facilitated through the dedicated iOS TestFlight app.
To get an app ready for testers, developers can upload a beta build of the app from Xcode and add the names and email address of people to test the app in iTunes Connect. To enable users to start testing prerelease builds of an app, developers need to create an iTunes Connect record for the app.
Each time a tester is invited, they will automatically receive an invitation email to join the group of beta testers and will be prompted to install the free TestFlight app from the Apple App Store. Once a beta app is installed, TestFlight will notify testers each time a new build is available, provide instructions on where to focus, and offer a way to give feedback.
More information is available on the Apple developer
site.