AdAttributionKit

Privacy-preserving ad attribution for iOS 17.4+ / Swift 6.3. AdAttributionKit lets ad networks measure conversions (installs and re-engagements) without exposing user-level data. It supports the App Store and alternative marketplaces, and interoperates with SKAdNetwork.

Three roles exist in the attribution flow: the ad network (signs impressions, receives postbacks), the publisher app (displays ads), and the advertised app (the app being promoted).

Contents

• Overview and Privacy Model
• Publisher App Setup
• Advertiser App Setup
• Impressions
• Postbacks
• Conversion Values
• Re-engagement
• Common Mistakes
• Review Checklist
• References

Overview and Privacy Model

AdAttributionKit preserves user privacy through several mechanisms:

• Crowd anonymity tiers -- the device limits postback data granularity based

on the crowd size associated with the ad, ranging from Tier 0 (minimal data) to Tier 3 (most data including publisher ID and country code).

• Time-delayed postbacks -- postbacks are sent 24-48 hours after conversion

window close (first window) or 24-144 hours (second/third windows).

• No user-level identifiers -- postbacks contain aggregate source

identifiers and conversion values, not device or user IDs.

• Hierarchical source identifiers -- 2, 3, or 4-digit source IDs where the

number of digits returned depends on the crowd anonymity tier.

In migration and interoperability reviews, explicitly state that the system evaluates AdAttributionKit and SKAdNetwork impressions together, only one impression wins per conversion, click-through beats view-through, and recency breaks ties within click-through impressions before falling back to the most recent view-through impression.

Publisher App Setup

A publisher app displays ads from registered ad networks. Add each ad network's ID to the app's Info.plist so its impressions qualify for install validation.

Add ad network identifiers

<key>AdNetworkIdentifiers</key>
<array>
    <string>example123.adattributionkit</string>
    <string>another456.adattributionkit</string>
</array>

Ad network IDs must be lowercase. SKAdNetwork IDs (ending in .skadnetwork) are also accepted -- the frameworks share IDs.

Display a UIEventAttributionView

For click-through custom-rendered ads, place one UIEventAttributionView over each tappable ad/control. It must cover the tappable area and stay above views that would intercept touches before handleTap() succeeds.

import UIKit

let attributionView = UIEventAttributionView()
attributionView.frame = adContentView.bounds
attributionView.isUserInteractionEnabled = true
adContentView.addSubview(attributionView)

Advertiser App Setup

The advertised app is the app someone installs or re-engages with after seeing an ad. It must call a conversion value update at least once to begin the postback conversion window.

Opt in to receive winning postback copies

Add AttributionCopyEndpoint under the top-level AdAttributionKit Info.plist dictionary so the device sends a copy of the winning postback to your server:

<key>AdAttributionKit</key>
<dict>
    <key>AttributionCopyEndpoint</key>
    <string>https://example.com</string>
</dict>

The system derives the well-known endpoint from the registrable domain in the URL, ignoring subdomains:

https://example.com/.well-known/appattribution/report-attribution/

Configure your server to accept HTTPS POST requests at that path. The domain must have a valid SSL certificate.

Opt in for re-engagement postback copies

Add a second key in the same AdAttributionKit dictionary to also receive copies of winning re-engagement postbacks:

<key>AdAttributionKit</key>
<dict>
    <key>AttributionCopyEndpoint</key>
    <string>https://example.com</string>
    <key>OptInForReengagementPostbackCopies</key>
    <true/>
</dict>

Update conversion value on first launch

Call a conversion value update as early as possible after first launch to begin the conversion window:

import AdAttributionKit

func applicationDidFinishLaunching() async {
    do {
        try await Postback.updateConversionValue(0, lockPostback: false)
    } catch {
        print("Failed to set initial conversion value: \(error)")
    }
}

Impressions

Ad networks create signed impressions using JWS (JSON Web Signature). The publisher app uses AppImpression to register and handle those impressions.

Create an impression from a JWS

import AdAttributionKit

let impression = try await AppImpression(compactJWS: signedJWSString)

The JWS contains the ad network ID, advertised item ID, publisher item ID, source identifier, timestamp, and optional re-engagement eligibility flag. See references/adattributionkit-patterns.md for JWS generation details.

Check device support

guard AppImpression.isSupported else {
    // Fall back to alternative ad display
    return
}

View-through impressions

Record a view impression when the ad content has been displayed and dismissed:

func handleAdViewed(impression: AppImpression) async {
    do {
        try await impression.handleView()
    } catch {
        print("Failed to record view-through impression: \(error)")
    }
}

For long-lived ad views, use beginView() and endView() to track view duration:

try await impression.beginView()
// ... ad remains visible ...
try await impression.endView()

Click-through impressions

Respond to ad taps by calling handleTap() within 15 minutes of creating the AppImpression; otherwise request a fresh impression. If the advertised app is not installed, the system opens its App Store or marketplace page. If installed, the system launches it directly.

func handleAdTapped(impression: AppImpression) async {
    do {
        try await impression.handleTap()
    } catch {
        print("Failed to record click-through impression: \(error)")
    }
}

A UIEventAttributionView must overlay the ad for handleTap() to succeed.

StoreKit-rendered ads

Pass the impression to StoreKit overlay or product view controller APIs. StoreKit automatically records view-through impressions after 2 seconds of display and click-through impressions on tap.

import StoreKit

let config = SKOverlay.AppConfiguration(appIdentifier: "1234567890",
                                         position: .bottom)
config.appImpression = impression

Postbacks

Postbacks are attribution reports the device sends to ad networks (and optionally to the advertised app developer) after a conversion event.

Conversion windows

Three windows produce up to three postbacks for winning attributions:

Tier 0 postbacks only produce the first postback. Nonwinning attributions produce only one postback.

Time windows for events

Lock conversion values early

Lock the postback to finalize a conversion value before the window ends and receive the postback sooner:

try await Postback.updateConversionValue(
    42,
    coarseConversionValue: .high,
    lockPostback: true
)

After locking, the system ignores further updates in that conversion window.

Postback data by tier

Conversion Values

Fine-grained values

Fine values are integers from 0...63 (6 bits). They are available only in the first postback and only at Tier 2 or higher:

try await Postback.updateConversionValue(
    35,
    coarseConversionValue: .medium,
    lockPostback: false
)

Coarse values

Three levels for lower tiers and second/third postbacks:

// CoarseConversionValue cases: .low, .medium, .high
try await Postback.updateConversionValue(
    10,
    coarseConversionValue: .high,
    lockPostback: false
)

Update by conversion type (iOS 18+)

Separate conversion values for install vs. re-engagement postbacks. In server JSON, use "conversion-type": "re-engagement" with the hyphen; Swift APIs use .reengagement without it.

let installUpdate = PostbackUpdate(
    fineConversionValue: 20,
    lockPostback: false,
    conversionTypes: [.install]
)
try await Postback.updateConversionValue(installUpdate)

let reengagementUpdate = PostbackUpdate(
    fineConversionValue: 12,
    lockPostback: false,
    conversionTypes: [.reengagement]
)
try await Postback.updateConversionValue(reengagementUpdate)

Conversion tags (iOS 18.4+)

Use conversion tags to selectively update specific postbacks when overlapping conversion windows exist:

let update = PostbackUpdate(
    fineConversionValue: 15,
    lockPostback: false,
    conversionTag: savedConversionTag,
    conversionTypes: [.reengagement]
)
try await Postback.updateConversionValue(update)

The system delivers the conversion tag through the re-engagement URL's AdAttributionKitReengagementOpen query parameter.

Re-engagement

Re-engagement tracks users who already have the advertised app installed and interact with an ad to return to it.

Mark impressions as re-engagement eligible

Set eligible-for-re-engagement to true in the JWS payload when generating the impression.

Handle re-engagement taps with a URL

Pass a universal link that the system opens in the advertised app:

let reengagementURL = URL(string: "https://example.com/promo/summer")!
try await impression.handleTap(reengagementURL: reengagementURL)

The system appends AdAttributionKitReengagementOpen as a query parameter. The advertised app checks for this parameter to detect AdAttributionKit-driven opens:

func handleUniversalLink(_ url: URL) {
    let components = URLComponents(url: url, resolvingAgainstBaseURL: false)
    let isReengagement = components?.queryItems?.contains(where: {
        $0.name == Postback.reengagementOpenURLParameter
    }) ?? false

    if isReengagement {
        // AdAttributionKit opened this app via a re-engagement ad
    }
}

Re-engagement limits

• Only click-through interactions create re-engagement postbacks (not

view-through).

• The device enforces monthly per-app and yearly per-device re-engagement

limits.

• The AdAttributionKitReengagementOpen parameter is always present on the

URL, even when the system does not create a postback.

Common Mistakes

Forgetting to update conversion value on launch

// DON'T -- never updating the conversion value
func appDidLaunch() {
    // No conversion value update; postback window never starts
}

// DO -- update conversion value on first launch
func appDidLaunch() async {
    try? await Postback.updateConversionValue(0, lockPostback: false)
}

Using uppercase ad network IDs

<!-- DON'T -->
<string>Example123.AdAttributionKit</string>

<!-- DO -->
<string>example123.adattributionkit</string>

Calling handleTap without a current UIEventAttributionView tap

// DON'T -- tap without a current attribution view tap or fresh impression
try await staleImpression.handleTap()
// Throws if the tap cannot be validated or the impression expired

// DO -- ensure UIEventAttributionView covers the ad and the impression is fresh
let attributionView = UIEventAttributionView()
attributionView.frame = adView.bounds
adView.addSubview(attributionView)
// Then handle the tap within 15 minutes after creating the AppImpression
try await impression.handleTap()

Ignoring handleTap errors

// DON'T
try? await impression.handleTap()

// DO -- handle specific errors
do {
    try await impression.handleTap()
} catch let error as AdAttributionKitError {
    switch error {
    case .impressionExpired:
        // Impression expired or is stale for click-through handling
        refreshAdImpression()
    case .missingAttributionView:
        // UIEventAttributionView not present
        break
    default:
        print("Attribution error: \(error)")
    }
}

Not responding to postback requests

// DON'T -- silently dropping the request
// The device retries up to 9 times over 9 days on HTTP 500

// DO -- respond with 200 OK immediately
// Server handler:
func handlePostback(request: Request) -> Response {
    // Process asynchronously, respond immediately
    Task { await processPostback(request.body) }
    return Response(status: .ok)
}

Review Checklist

• [ ] Publisher app includes all ad network IDs in AdNetworkIdentifiers

(lowercase)

• [ ] Ad network IDs match between publisher app's Info.plist and JWS kid
• [ ] UIEventAttributionView overlays each tappable click-through ad/control
• [ ] Click-through AppImpression is no older than 15 minutes at handleTap()
• [ ] Advertised app calls updateConversionValue on first launch
• [ ] Server endpoint at well-known path accepts HTTPS POST with valid SSL
• [ ] Postback verification uses correct Apple public key for environment
• [ ] Duplicate postbacks filtered by postback-identifier
• [ ] Server responds with HTTP 200 to postback requests
• [ ] Re-engagement URL is a registered universal link for the advertised app
• [ ] Conversion value strategy accounts for all three conversion windows
• [ ] AppImpression.isSupported checked before attempting impression APIs

References

• references/adattributionkit-patterns.md

-- postback verification, server handling, testing, SKAdNetwork migration, alternative marketplaces, attribution rules configuration

• Apple: AdAttributionKit
• Apple: Presenting ads in your app
• Apple: Receiving ad attributions and postbacks
• Apple: Verifying a postback
• Apple: SKAdNetwork interoperability