9th April 2021

POV: Apple App Tracking Transparency


Apple shared more details this week about its App Tracking Transparency privacy feature that will soon be enforced with the launch of iOS 14.5 and which allows users to control their data and whether it is shared for ad-targeting purposes.

Details and Implications:

The company first announced at its WWDC in June 2020 that app developers would have to ask for user permission in order to track and share their advertising identifier (IDFA) for ad targeting purposes, but then delayed the tracking restrictions coming into effect when iOS 14 launched last September - giving developers more time to make necessary changes.

Now, with the launch of iOS 14.5 expected in the next few weeks, the privacy feature will be mandatory and Apple will require any app that collects and shares users’ data for tracking purposes to clearly display the App Tracking Transparency prompt and explicitly ask for and get the user’s permission to track them or access their device’s advertising identifier.

Previously, Apple’s Identifier for Advertisers (IDFA) was freely available without consent (though users could opt-out) allowing developers and advertisers to link specific ad impressions to app and browser actions. The new feature moves to an explicit opt-in model and users will be asked if they want to allow the app to track their activity across other companies’ apps and websites. Users will be able to control at an app-by-app level whether their data is shared for ad targeting purposes and can toggle the feature on or off at any time in the Tracking menu in the privacy settings and also enable tracking across all apps or opt out entirely with one toggle.

Apple also offers a separate ‘Personalized Ads’ toggle that allows users to decide whether they want to be tracked within Apple's first-party apps. This is totally distinct from the IDFA opt-in prompt.

However, the new rules are not limited to only the IDFA identifier. When a user opts out of tracking, Apple also expects developers to stop using any other identifiers – such as hashed email addresses for example - to track users and not to share data with data brokers. Reports suggest that developers will still be able to track users across their own family of apps if operated by a single company, just not across all apps.

Apple has also updated its ‘A Day in the Life of Your Data’ report that explains how users are tracked and targeted to include new information, including details of two ad measurement technologies that advertisers can use to measure the impact of their campaigns without tracking users.

One is SKAdNetwork, which tracks how many times an app was installed after ads for it were seen, but without any user or device-level data begin shared. The second is Private Click Measurement that will be available for apps in iOS and iPadOS 14.5 in addition to websites. This feature for measuring ad clicks across websites and from iOS apps to websites can be used to understand which ads drive conversions, whilst maintaining user privacy.


The impact of Apple’s move remains to be seen and much will depend on take up of the privacy options by consumers. No-one knows the opt-in rate that can be expected or the speed of change, so for the moment it is a wait and see situation. Meanwhile, in China, developers are looking at a workaround called CAID (China Advertising ID) that uses device attributes (fingerprinting) to bypass the Apple changes. If the Chinese eco-system gets behind this approach, Apple may have difficult time enforcing its approach.

Further Reading:

TechCrunch | Apple Developer Blog | MacRumors | Mindshare POV - Apple iOS Tracking Update | AdExchanger

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