feat(audience-sdk): iOS SKAdNetwork registration on first launch (SDK-307)

Calls SKAdNetwork.registerAppForAdNetworkAttribution() via Obj-C++ bridge
on the first app launch when config.EnableMobileAttribution is true.
Subsequent launches skip the call (PlayerPrefs flag persists per install).
Emits skanRegistered: true on the game_launch event only when registration
fires. Runtime dispatch avoids a hard StoreKit link and the In-App Purchase
capability requirement.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: nattb8

examples/audience/Assets/SampleApp/Resources/AudienceSample.uxml

@@ -99,6 +99,12 @@
                                      text="Mirror SDK internal log output into the in-page event log below." />
                         </ui:VisualElement>
 
+                        <ui:VisualElement class="field">
+                            <ui:Toggle name="enable-mobile-attribution" label="MOBILE ATTRIBUTION" />
+                            <ui:Label class="helper-text below-field"
+                                     text="Enable iOS SKAdNetwork registration and mobile attribution signals." />
+                        </ui:VisualElement>
+
                         <ui:VisualElement class="field placeholder-host">
                             <ui:Label class="field-label" text="BASE URL OVERRIDE" />
                             <ui:TextField name="base-url" />

examples/audience/Assets/SampleApp/Scripts/AudienceSample.UI.cs

@@ -52,7 +52,7 @@ private static readonly (string TabId, string PanelId)[] Tabs =
 
         private TextField _publishableKey, _baseUrl, _flushInterval, _flushSize;
         private DropdownField _initialConsent;
-        private Toggle _debug;
+        private Toggle _debug, _enableMobileAttribution;
         private Button _btnInit, _btnFlush, _btnReset, _btnShutdown, _btnDeleteData;
 
         // ---- UXML element fields (Consent tab) ----
@@ -180,7 +180,8 @@ private void BindElements()
             _publishableKey = Require<TextField>("publishable-key");
             _baseUrl        = Require<TextField>("base-url");
             _initialConsent = Require<DropdownField>("initial-consent");
-            _debug          = Require<Toggle>("debug");
+            _debug                    = Require<Toggle>("debug");
+            _enableMobileAttribution  = Require<Toggle>("enable-mobile-attribution");
             // Inject a tick Label — Unity 2021.3 runtime panels render the
             // checked state as a plain coloured square otherwise. USS hides
             // the tick when unchecked.
@@ -640,15 +641,17 @@ internal readonly struct InitForm
             public readonly string BaseUrl;
             public readonly ConsentLevel Consent;
             public readonly bool Debug;
+            public readonly bool EnableMobileAttribution;
             public readonly int? FlushIntervalMs;
             public readonly int? FlushSize;
 
-            public InitForm(string publishableKey, string baseUrl, ConsentLevel consent, bool debug, int? flushIntervalMs, int? flushSize)
+            public InitForm(string publishableKey, string baseUrl, ConsentLevel consent, bool debug, bool enableMobileAttribution, int? flushIntervalMs, int? flushSize)
             {
                 PublishableKey = publishableKey;
                 BaseUrl = baseUrl;
                 Consent = consent;
                 Debug = debug;
+                EnableMobileAttribution = enableMobileAttribution;
                 FlushIntervalMs = flushIntervalMs;
                 FlushSize = flushSize;
             }
@@ -660,12 +663,13 @@ internal InitForm CaptureInitForm()
             int? flushIntervalMs = int.TryParse((_flushInterval.value ?? "").Trim(), out var ms) && ms > 0 ? ms : (int?)null;
             int? flushSize = int.TryParse((_flushSize.value ?? "").Trim(), out var size) && size > 0 ? size : (int?)null;
             return new InitForm(
-                publishableKey:  (_publishableKey.value ?? "").Trim(),
-                baseUrl:         (_baseUrl.value ?? "").Trim(),
-                consent:         ConsentOrder[consentIdx],
-                debug:           _debug.value,
-                flushIntervalMs: flushIntervalMs,
-                flushSize:       flushSize);
+                publishableKey:          (_publishableKey.value ?? "").Trim(),
+                baseUrl:                 (_baseUrl.value ?? "").Trim(),
+                consent:                 ConsentOrder[consentIdx],
+                debug:                   _debug.value,
+                enableMobileAttribution: _enableMobileAttribution.value,
+                flushIntervalMs:         flushIntervalMs,
+                flushSize:               flushSize);
         }
 
         // Snapshot of the identify form on the Identity tab.

examples/audience/Assets/SampleApp/Scripts/AudienceSample.cs

@@ -301,11 +301,12 @@ private AudienceConfig BuildAudienceConfig(InitForm form, Action<AudienceError>
         {
             var config = new AudienceConfig
             {
-                PublishableKey = form.PublishableKey,
-                BaseUrl        = string.IsNullOrEmpty(form.BaseUrl) ? null : form.BaseUrl,
-                Consent        = form.Consent,
-                Debug          = form.Debug,
-                OnError        = onError,
+                PublishableKey          = form.PublishableKey,
+                BaseUrl                 = string.IsNullOrEmpty(form.BaseUrl) ? null : form.BaseUrl,
+                Consent                 = form.Consent,
+                Debug                   = form.Debug,
+                EnableMobileAttribution = form.EnableMobileAttribution,
+                OnError                 = onError,
             };
             if (form.FlushIntervalMs is int flushMs && flushMs > 0)
             {
@@ -324,12 +325,13 @@ private static Dictionary<string, object> BuildConfigEcho(AudienceConfig config)
         {
             var echo = new Dictionary<string, object>
             {
-                ["consent"]                = config.Consent.ToString(),
-                ["debug"]                  = config.Debug,
-                ["flushIntervalSeconds"]   = config.FlushIntervalSeconds,
-                ["flushSize"]              = config.FlushSize,
-                ["packageVersion"]         = config.PackageVersion,
-                ["shutdownFlushTimeoutMs"] = config.ShutdownFlushTimeoutMs,
+                ["consent"]                  = config.Consent.ToString(),
+                ["debug"]                    = config.Debug,
+                ["enableMobileAttribution"]  = config.EnableMobileAttribution,
+                ["flushIntervalSeconds"]     = config.FlushIntervalSeconds,
+                ["flushSize"]                = config.FlushSize,
+                ["packageVersion"]           = config.PackageVersion,
+                ["shutdownFlushTimeoutMs"]   = config.ShutdownFlushTimeoutMs,
             };
             if (!string.IsNullOrEmpty(config.PublishableKey))
                 echo["publishableKey"] = RedactPublishableKey(config.PublishableKey);

src/Packages/Audience/Runtime/ImmutableAudience.cs

@@ -48,6 +48,11 @@ public static class ImmutableAudience
         internal static volatile Func<IReadOnlyDictionary<string, object>>? LaunchContextProvider;
         internal static volatile Func<IReadOnlyDictionary<string, object>>? ContextProvider;
 
+        // Called during Init when config.EnableMobileAttribution is true.
+        // Returns true on first SKAN registration, null if already done or not applicable.
+        // Set by the Unity layer; null in pure-C# environments.
+        internal static volatile Func<bool?>? MobileAttributionProvider;
+
         // Active session. Created at Init (or on upgrade from None) and disposed
         // on Shutdown or SetConsent(None). Volatile so OnPause/OnResume see
         // assignments from SetConsent without taking _initLock.
@@ -204,7 +209,14 @@ public static void Init(AudienceConfig config)
             // shows the new sessionId ahead of the launch event.
             sessionToStart?.Start();
 
-            FireGameLaunch(config, consentAtInit);
+            bool? skanRegistered = null;
+            if (config.EnableMobileAttribution)
+            {
+                try { skanRegistered = MobileAttributionProvider?.Invoke(); }
+                catch (Exception ex) { Log.Warn(AudienceLogs.MobileAttributionProviderThrew(ex)); }
+            }
+
+            FireGameLaunch(config, consentAtInit, skanRegistered);
         }
 
         // Pause/Resume hooks for the Unity lifecycle bridge.
@@ -982,7 +994,7 @@ private static void RescheduleSendTimer(HttpTransport transport)
         }
 
         // consentAtInit only gates the launch; Track still checks live _state via CanTrack.
-        private static void FireGameLaunch(AudienceConfig config, ConsentLevel consentAtInit)
+        private static void FireGameLaunch(AudienceConfig config, ConsentLevel consentAtInit, bool? skanRegistered = null)
         {
             if (!consentAtInit.CanTrack()) return;
 
@@ -1011,6 +1023,10 @@ private static void FireGameLaunch(AudienceConfig config, ConsentLevel consentAt
             if (config.DistributionPlatform != null)
                 properties["distributionPlatform"] = config.DistributionPlatform;
 
+            // Emitted only on the first launch where SKAN registration fires.
+            if (skanRegistered == true)
+                properties["skanRegistered"] = true;
+
             // No sessionId on game_launch per Event Reference. Pipeline correlates
             // via eventTimestamp with the session_start that fires just before.
             Track("game_launch", properties.Count > 0 ? properties : null);

src/Packages/Audience/Runtime/Plugins/iOS/AudienceMobileBridge.mm

@@ -12,4 +12,15 @@
     return idfv ? strdup([idfv UTF8String]) : NULL;
 }
 
+void _AudienceRegisterSKAN(void)
+{
+    // Runtime dispatch avoids a hard link to StoreKit.framework, which would
+    // trigger Xcode's In-App Purchase capability check. StoreKit is always
+    // present on device; NSClassFromString finds it without a compile-time dep.
+    Class cls = NSClassFromString(@"SKAdNetwork");
+    if (cls) {
+        [cls performSelector:@selector(registerAppForAdNetworkAttribution)];
+    }
+}
+
 }

src/Packages/Audience/Runtime/Unity/AudienceUnityHooks.cs

@@ -2,6 +2,7 @@
 
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using Immutable.Audience.Unity.Mobile;
 using UnityEngine;
 
 namespace Immutable.Audience.Unity
@@ -27,6 +28,10 @@ private static void Install()
             ImmutableAudience.LaunchContextProvider = () => launchProps;
             ImmutableAudience.ContextProvider = () => contextProps;
 
+#if UNITY_IOS && !UNITY_EDITOR
+            ImmutableAudience.MobileAttributionProvider = () => SkanRegistration.RegisterIfFirstLaunch();
+#endif
+
             UnityLifecycleBridge.EnsureExists();
 
             if (Log.Writer == null) Log.Writer = Debug.Log;

src/Packages/Audience/Runtime/Unity/Mobile/SKANBridge.cs

@@ -0,0 +1,25 @@
+#nullable enable
+
+using System;
+#if UNITY_IOS
+using System.Runtime.InteropServices;
+#endif
+
+namespace Immutable.Audience.Unity.Mobile
+{
+    internal static class SKANBridge
+    {
+        internal static Action Impl = NativeImpl;
+
+        internal static void Register() => Impl();
+
+#if UNITY_IOS
+        [DllImport("__Internal")]
+        private static extern void _AudienceRegisterSKAN();
+
+        private static void NativeImpl() => _AudienceRegisterSKAN();
+#else
+        private static void NativeImpl() { }
+#endif
+    }
+}

src/Packages/Audience/Runtime/Unity/Mobile/SKANBridge.cs.meta

@@ -0,0 +1,33 @@
+#nullable enable
+
+using System;
+using UnityEngine;
+
+namespace Immutable.Audience.Unity.Mobile
+{
+    internal static class SkanRegistration
+    {
+        private const string PrefsKey = "ImmutableAudience.skan_registered";
+
+        // Replaceable in tests.
+        internal static Func<bool> HasRegistered = DefaultHasRegistered;
+        internal static Action MarkRegistered = DefaultMarkRegistered;
+
+        // Returns true on first registration (SKAN was called), null if already done or N/A.
+        internal static bool? RegisterIfFirstLaunch()
+        {
+            if (HasRegistered()) return null;
+            SKANBridge.Register();
+            MarkRegistered();
+            return true;
+        }
+
+        private static bool DefaultHasRegistered() => PlayerPrefs.HasKey(PrefsKey);
+
+        private static void DefaultMarkRegistered()
+        {
+            PlayerPrefs.SetInt(PrefsKey, 1);
+            PlayerPrefs.Save();
+        }
+    }
+}