What is App Tracking Transparency?

App Tracking Transparency (ATT) is Apple's framework that requires apps to get user permission before tracking their activity across other companies' apps and websites. It was introduced in iOS 14.5 (April 2021) and fundamentally changed mobile advertising.

Before ATT, apps could freely access the IDFA (Identifier for Advertisers) to track users. Now, that identifier returns all zeros unless the user explicitly grants permission.

When Do You Need ATT Permission?

Not every app needs ATT. Here's a quick decision tree:

Implementation Guide

Step 1: Add the Usage Description

Add NSUserTrackingUsageDescription to your Info.plist. This is the text that appears in the permission dialog.

<key>NSUserTrackingUsageDescription</key>
<string>We use this to show you relevant ads and measure their effectiveness. Your data is never sold.</string>

Step 2: Request Permission

Use ATTrackingManager to request authorization. This must be called before you access IDFA.

import AppTrackingTransparency
import AdSupport

func requestTrackingPermission() {
    // Only request on iOS 14+
    guard #available(iOS 14, *) else {
        // Pre-iOS 14: IDFA is available without permission
        let idfa = ASIdentifierManager.shared().advertisingIdentifier
        initializeAds(with: idfa)
        return
    }

    // Check current status first
    let status = ATTrackingManager.trackingAuthorizationStatus

    switch status {
    case .notDetermined:
        // User hasn't been asked yet - request permission
        ATTrackingManager.requestTrackingAuthorization { newStatus in
            DispatchQueue.main.async {
                self.handleAuthorizationStatus(newStatus)
            }
        }
    case .authorized:
        // Already authorized
        let idfa = ASIdentifierManager.shared().advertisingIdentifier
        initializeAds(with: idfa)
    case .denied, .restricted:
        // User denied or restricted - use limited tracking
        initializeAdsWithoutTracking()
    @unknown default:
        initializeAdsWithoutTracking()
    }
}

func handleAuthorizationStatus(_ status: ATTrackingManager.AuthorizationStatus) {
    switch status {
    case .authorized:
        let idfa = ASIdentifierManager.shared().advertisingIdentifier
        print("IDFA: \(idfa.uuidString)")
        initializeAds(with: idfa)
    case .denied:
        print("Tracking denied by user")
        initializeAdsWithoutTracking()
    case .restricted:
        print("Tracking restricted (parental controls, etc.)")
        initializeAdsWithoutTracking()
    case .notDetermined:
        print("Status not determined")
        initializeAdsWithoutTracking()
    @unknown default:
        initializeAdsWithoutTracking()
    }
}

Step 3: Handle the Response

Your app needs to work regardless of whether the user grants permission. Plan for both scenarios:

When to Show the ATT Prompt

Timing is everything. Ask too early and users will instinctively tap "Ask App Not to Track" without reading. Here's what actually works:

Writing Effective Permission Strings

Your NSUserTrackingUsageDescription text appears in the system dialog. It's limited to about 200 characters before truncation. Make them count.

Key principles for high-converting permission strings:

• Focus on user benefit — What do THEY get? Not what do you get.
• Be specific — "Personalized ads" is better than "improve experience."
• Be honest — Don't claim you need it if you don't.
• Avoid fear — Don't say "or we can't show you anything."

Handling Users Who Decline

Expect most users to decline. Industry data shows about 65-75% will tap "Ask App Not to Track." Your app needs to handle this gracefully.

// Check if user can still be asked
func canRequestTracking() -> Bool {
    if #available(iOS 14, *) {
        return ATTrackingManager.trackingAuthorizationStatus == .notDetermined
    }
    return true // Pre-iOS 14, no permission needed
}

// Gently remind user they can enable tracking in Settings
func showTrackingReminderIfNeeded() {
    guard #available(iOS 14, *) else { return }

    if ATTrackingManager.trackingAuthorizationStatus == .denied {
        // Show a non-intrusive banner or message
        // "Want personalized ads? Enable in Settings > Privacy > Tracking"
        // But don't be annoying about it
    }
}

Frequently Asked Questions