Inviting users to an IOS app

Question

After registration, our app prompts users to invite her friends (aka phone contacts) to use the app too. This allows us to send an email/sms to the useer's contacts with some sort of invitation key. Works fine for a web version app, just embed the key in the url you provide in the invitation.

I'm having trouble figuring out how to make this work smoothly with IOS only. It would be brilliant if I could send the invitee a link to appstore.apple.com/myapp?registrationKey=abcXYZ and have the key magically available to my app once it's installed, but I guess this is a lot to hope for?

The obvious way around this is to make the user manually enter their registration key on first launch, but this seems less reliable and (to my mind) adds friction to the UX.

Has anybody come up with something clever to get around this?

Answer 1

(Full disclosure, currently work at Branch)

The best solution to this is to fingerprint a user. This requires you to do the following steps:

• For each user, using your own domain, generate a link for said user. So, right when they complete registration, generate their unique URL, that contains the invitation key.

• For anyone clicking this link, they will redirect to Safari first. When they do, capture their IP address and iOS operating system version from the headers and user-agent.

• Save this data on your server, and set window.location to your iTunes url.

• If the user downloads and consequently opens, inside AppDelegate.m, send a message to your server with the IP address + major/minor/min version you collect upon app launch. If it matches with what you have on the server, you can now pass that invitation key back to the new user.

It's not perfect, and has the ability to misattribute. You could also use branch.io, where all of this is taken care of (link-generation, fingerprinting a user, attribution). Branch also drops a first party cookie and ties it with the device level ID, so attributions are much more accurate.

Answer 2

As far as I can tell, the App Store provides an information firewall between an invitation and the installed app.

The closest workaround I've seen is the following:

• email link sends you to your website
• the website logs reference information in the URL and the IP address
• the website instantly redirects you to the App Store (if iOS detected)
• user installs the app
• user loads the app
• app contacts your website, IP addresses matched ... BINGO

Obviously not a secure method though. There are many failure cases:

• business networks commonly share IPs
• home and mobile networks release and reuse IPs

The more is frequently used to resolve cases where its good enough to know that the user 'almost-certainly' was referred to download app by the email. For example, it can be a good mechanism to prompt the user with a "who do you know" question in an app and limit the options based on the (IP+reference) data. If they pick the original poster, then maybe that's good enough, and then you can attach any other data that the inviter provided.

Answer 3

Here is what is flowing through my brain on how to solve this solution, please note, I have not vetted, psudeo-coded, coded, or applied this theory.

Since you will know who is being sent an invitation, save that data to your database with a relationship to the user sending and a unique id to the user being invited (email address if its in the contact's card). When new users sign up scan the database for invitations, if one is found present it to the user asking We're you referred by <existing user>? Once the new user selects their response continue through the registration process, updating the relationship table accordingly and applying any extra settings you need to for the referral.

This combines automatic referral tracking with referral codes for a basic, straight-forward, almost (but not quite) fool proof method to make sure referrals are linked to the right users.