How to install iOS Beta Versions of WhatsApp?
First of all: You need to have a jailbroken Device.
What is jailbroken ?
Jailbreaking in general term and it means breaking the device out of its “jail” or walls, a metaphor used in Unix-like systems, for example in “FreeBSD jail”. A jailbroken iPhone, iPod Touch, or iPad running iOS can still use the App Store, iTunes, and other normal functions, such as making telephone calls.
If you are jailbroken, add this Source to Cydia: http://cydia.angelxwind.net/
Install “AppSync Unified” from this Source and reboot your Device after that.
Once your Device is rebooted, follow this website or Twitter for new Beta Releases, visit the Website https://dev2.whatsapp.net/ios/WhatsApp/ and click on “Tap here to install”.
WhatsApp Beta will replace your AppStore WhatsApp Version. A downgrade is currently NOT possible.
You need to use WhatsApp Beta until the AppStore Version is newer then the Beta Version!