I will have multiple users using the same iPad.
When you log out of Nintex Mobile the next user has to go through the whole process of logging back in including entering the site URL which is a bit laborious.
I have found a shortcut that will open a nintex app but only works after Nintex mobile is opened in the background and I cannot get Safari to hold the URL long enough to create a desktop icon shortcut or add to favourites as once you paste the URL and hit enter safari warns you that another app is going to open/opens and then the URL reverts to whatever was previous
this will populate the URL and load the login page to the correct site - note: the url must be encoded as shown.
Have you tried Nintex Mobile Enterprise? You can preconfigure your SharePoint or Office 365 tenant url so that users will only have to enter their credentials.
Unfortunately the Enterprise Licence pricing is a little prohibitive for the scale of our operation and usage at this time.