This blog was originally published in 2021. It has been updated to reflect changes in the mobile ecosystem.
The release notes for beta 4 of iOS 15 included a tiny note:
“Background pushes will only be delivered if the app has been used in the foreground in the past few weeks.”
It sounds like a minor update, but this is relevant to mobile marketers and product managers. It means uninstall tracking is significantly limited on iOS, beginning with iOS 15. This is a good thing for the mobile ecosystem: uninstall tracking, while popular, has always been a policy-violating, privacy-invasive hack. At Branch, we made the deliberate decision to not support it, despite the market demand, because we felt it was not in line with our mission and the privacy principles we live by.
Let’s back up and define a few things:
Background pushes are the silent, invisible version of push notifications that can be delivered to apps behind the scenes. They don’t show up on the device as banners or alerts, but they’re useful as a way to wake up inactive apps in the background for a short time window (on iOS, up to 30 seconds of processing time) to update content or perform some other action.
Uninstall tracking involves hacking these background push notifications to detect when an app has been uninstalled. It works as a sort of “dead man’s switch” by sending background pushes continuously until one isn’t delivered successfully (which indicates an uninstall has occurred). It’s pretty easy to see how Apple’s iOS 15 change will get in the way: when the OS stops delivering background notifications to an inactive app after “a few weeks,” every user will appear to have uninstalled.
Tracking uninstalls has been popular in the past because it can provide a sort of “anti-conversion metric.” In other words, typical mobile attribution measures desirable outcomes (e.g., campaigns that positively influence a user so much that they purchase in-app). Uninstall tracking is a tool to help avoid undesirable outcomes (e.g., campaigns that irritate users so much they uninstall the app in frustration). While there are often better ways to achieve the same objectives, tracking uninstalls isn’t necessarily a bad metric…in theory.
So, what’s the issue with uninstall tracking? In practice, there are actually three:
- Abusing the push notification system this way is explicitly forbidden in developer policies by both Apple and Google. These policies have not been widely enforced in the past, but the stakes are rising.
- The data quality has always been extremely dubious (for example, users can opt out of push notifications).
- The most typical use case (audience generation) is extremely offensive to users: most consumers have no idea they could be added to a retargeting audience for ad campaigns when they uninstall an app, but there is a long history of outraged responses when they find out. In fact, this is exactly the kind of “creepy tracking” that Apple targeted for extermination with the AppTrackingTransparency policy in iOS 14.
At Branch, we’ve always thought uninstall tracking was a poor metric. It’s invasive to user privacy, the data is unreliable, and it puts apps at risk for rejection from the store due to policy violations. That’s why we never built it — it does not align with our values, and it creates a major liability for our customers.
We’re glad Apple closed the uninstall tracking loophole in iOS 15, and the way they went about it is remarkably similar to some of the other privacy improvements in iOS 15: by using technical changes to flood the data with noise, Apple kneecaps privacy-invasive tracking without needing to take more direct action. Given the new, far more privacy-aware age we’re entering, we won’t be surprised if Google takes similar measures on Android.
We’ve already seen claims that limited uninstall tracking may still be technically possible on iOS, even after this change. While that could be true, we suggest taking this as an opportunity to reset the stage: if your team is still relying on uninstall tracking, this is the right time to move on. You won’t be making decisions based on incomplete data, users will appreciate your respect for their privacy, and you’ll be safe from the risk of running afoul of app store policies.