Not possible that I'm aware of, the Space invitations contain an alphanumeric secret that is included in the invite and is unique to each Space, see the KB article: What security is there for accessing spaces. As an alternative to sending out an invitation to the Space itself, you could have your guest access the Web Bridge in a browser and enter the Call ID and Passcode of the Space.
The Cisco Meeting App for IOS is compatible with both iPhone and iPad. The users would just need to try and access a Space, and if they already have the application installed, it should launch and put them into the space. If they don't have the application installed, it redirects the user to download it if you have the web bridge configured to that.
