If you have already installed the public beta of iOS 9, know that it is very easy to pass on the latest beta of iOS 4 9 offered to developers. To benefit, simply follow this little tutorial below:
Step 1: Open Settings> General> Profile
Step 2: Tap the iOS 9 Beta software profile
Step 3: Press Delete Profile
Step 4: Restart your device
Step 5: Open Settings> Software Update> and verify that it is the latest beta of iOS 4 9 for Developers
Step 6: Tap Download and Install to start the installation of iOS 4 beta 9
Please be aware that this version is a beta that has bugs but still perfectly functional. In addition, Apple limits the usage time until the next beta 5 (and so on). This means that after a time, the firmware is not signed by the firm. So remember to update the iOS 9 when the next beta will be available.