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Be ready for App Tracking Transparency & IDFA Depreciation - Checklist for app developers

“Privacy is a fundamental human right and at the core of everything we do. That’s why with iOS 14, we’re giving you more control over the data you share and more transparency into how it’s used.”

Those are the words that Apple used when they announced their new privacy guidelines for iOS 14 in September 2020. However, to give mobile advertisers and mobile app publishers more time to prepare, Apple later announced that it will be delaying implementation of its new iOS 14 privacy measures until early in 2021.

In practice, this means that while the App Tracking Transparency framework is included in all iOS 14 devices, its functionality has been amended during this transition period. Anyway, the changes will take effect soon and now is the last moment to prepare for them.


The App Tracking Transparency (ATT) is a new feature across iOS, iPadOS, and tvOS that will require apps to get the user's permission before tracking their data across apps or websites owned by other companies. Simply put, you must request user authorization to access app-related data for tracking the user or the device. It's noteworthy that developers will need to ask for user permission even if they already have user consent from earlier interactions.

The IDFA on the other hand is Apple’s identifier for advertisers. It's commonly used among app and game advertisers to measure the performance of their marketing campaigns. Following the ATT, Apple will require developers to ask permission to use the IDFA every single time a user installs a new app.

The replacing solution is SKAdNetwork, announced by Apple already in 2018. It is a framework for privacy-preserving mobile install attribution which helps to measure conversion rates of app install campaigns (CPI) without compromising users’ identities. In other words, SKAdNetwork is an aggregated solution for measuring attribution of mobile ad campaigns for iOS apps.


While the privacy updates generally are a good thing, and protect the users' identity, they are causing somewhat of a disruption for the app and game industry. First of all, as an app the developer you will need to be prepared by implementing the new opt-in features for asking the users' consent, and also, you must provide information about your privacy practices in App Store Connect. For that, you’ll also need to describe what data the third-party code collects, how the data may be used, and whether the data is used to track users. That is of course only if you use third-party code — such as advertising or analytics SDKs. There are detailed instructions on Apple's Developer guidelines.

The biggest implications will take place in the mobile app marketing and advertising. Mobile advertising is nowadays an estimated $80 billion industry and now it will face one of its biggest threats when its key features like conversion event optimization, retargeting, user re-engagement and building custom & lookalike audiences become difficult for iOS devices after the Apple's ATT policies take effect. Especially Facebook, the leading platform for highly targeted mobile advertising, is going to undergo big changes. Facebook has updated the instructions on how to keep running conversion optimized iOS app ads within the new privacy framework.

Another area that will be impacted is the mobile app attribution, or in other words the MMP's. As the app developer, you have basically a couple of options. You can try to maximize the IDFA data from opt-in users and use that data, however limited if might be. This will enable deterministic attribution where the IDFA is available in the source app and allow for probabilistic attribution against mobile web channels where an IDFA is not available. Alternative option is to rely on SKAdNetwork for paid media attribution. This will mean that deterministic and probabilistic attribution will not be available. Appsflyer, among other MMP's, has developed solutions for post iOS14 attribution. Read more about their alternatives from here.

No one knows, for sure, what the full impacts of the IDFA depreciation will be, as it's all relative to how many people choose to opt-out once shown the new prompts. Some studies say the opt-in rate will be terribly low at maximum 5-10%. On top of that, it's reported that in the US more than 30% of App Store users have Limit Ad Tracking (LAT) turned on. Then again, findings by Didomi indicate that when the request is appropriate, the consent rates within apps can be as high as 50%-70%.

At the end, the one thing we know for sure is that the change will come, and it will be the same for everyone. There's no need to panic. The best thing to do is to be ready to test all possibilities, be open-minded about the change and shift the mindset to the new way of working. Things will be alright.


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