iPhone being a close system does no good for the app developers aswell , as every app provides Beta programs and users of Android join that to enjoy features not rolled out for the rest of the word , but unfortunately there is no straight forward way for iPhone. You may follow these steps to install WhatsApp Beta on your iPhone :
- Uninstall WhatsApp on your iPhone, if you have it. Make sure you backup your WhatsApp data before you proceed, otherwise you will end up losing it completely. (BACKUP)
- Connect your iPhone to a PC / Mac – and launch iTunes.
- Make sure you tell the phone to the trust the computer, when and if prompted.
- Your phone should appear in iTunes, and then quit iTunes. Keep your iPhone plugged in.
- Get WhatsApp beta for IPhone from this link.
- Download and Run Cydia Impactor.
- Drag the WhatsApp IPA file from step 5 to the Cydia Impactor window.
- You will be asked to enter an Apple ID followed by the password. Use your existing one, or create a new one. I would suggest you to create a new one , just to be on safe side
- Cydia Impactor will then install WhatsApp Beta on your iPhone.
- If you try to launch the WhatsApp app beta on your phone straightaway you will get an error.
- Fix the error, by going to your iPhone's Settings > General > Device Management.
- Tap 'Trust <your_Apple_ID>' where your_Apple_ID will be the account you used in step 8.
- Go back and launch WhatsApp.
Enjoy Beta Features of WhatsApp on Iphone :)