Send WhatsApp message to not saved in iPhone contact list
Send whatsapp mesages to unsaved contacts in WhatsApp for iOS is not possible with the app directly, but there is a trick to do it :)
First you have to make a quick missed call to the number.
Then, go to your call log list, and tap to the "info" icon (is situated on the right)
Then tap to the whatsapp icon and voila! You are sending a whatsapp message to a unsaved contact :)