How to Protect Obj-C SelRefs Against Tampering Apps Using AI

Last updated February 23, 2025 by Appdome

This Knowledge Base article describes how to use Appdome’s AI/ML in your CI/CD pipeline to continuously deliver plugins that Protect Obj-C SelRef in iOS apps.

What Are Objective-C SelRefs in iOS Apps?

In Objective-C applications, selectors (SelRefs) are used to reference methods dynamically at runtime. These selectors are stored in a global table within the Mach-O file and can be accessed or modified externally, exposing them to tampering and manipulation. Attackers can target this structure to modify or redirect function calls, potentially hijacking the app’s behavior. For instance, by modifying selectors, hackers can change the intended method or function execution, compromising app security and leading to potential vulnerabilities such as code injection or unauthorized execution of malicious code. Protecting SelRefs is essential to prevent unauthorized method manipulation, securing the app’s internal logic, and supporting regulatory requirements like PCI-DSS.

How Appdome Protects Objective-C SelRefs Against Tampering?

Appdome’s dynamic Obj-C SelRef Protection plugin for iOS defends against tampering with the global selector table in Objective-C applications. The plugin continuously monitors the selector table for unauthorized changes, preventing manipulation of method references. If an attempt is made to modify or replace a method’s selector, the app is immediately shut down to prevent further damage. This protection is essential for stopping reverse-engineering efforts, ensuring accurate method references, and blocking attackers from hijacking method calls for malicious actions.

Prerequisites for Using Appdome's Obj-C SelRef Protection Plugins:

To use Appdome’s mobile app security build system to Protect Obj-C SelRef , you’ll need:

Appdome account (create a free Appdome account here)
A license for ONEShield™
Mobile App (.ipa for iOS)
Signing Credentials (see Signing Secure Android apps and Signing Secure iOS apps)

How to Implement Protect Obj-C SelRef in iOS Apps Using Appdome

On Appdome, follow these 3 simple steps to create self-defending iOS Apps that Protect Obj-C SelRef without an SDK or gateway:

Designate the Mobile App to be protected.
1. Upload an app via the Appdome Mobile Defense platform GUI or via Appdome’s DEV-API or CI/CD Plugins.
2. iOS Formats: .ipa
3. Obj-C SelRef Protection is compatible with: Obj-C, Java, Swift, Flutter, React Native, Unity, Xamarin, Cordova and other iOS apps.
Select the defense: Obj-C SelRef Protection.

Create and name the Fusion Set (security template) that will contain the Obj-C SelRef Protection feature as shown below:

Figure 1: Fusion Set that will contain the Obj-C SelRef Protection feature

Follow the steps in Sections 2.2-2.2.2 of this article to add the Obj-C SelRef Protection feature to your Fusion Set via the Appdome Console.

When you select the Obj-C SelRef Protection you'll notice that the Fusion Set you created in step 2.1 now bears the icon of the protection category that contains Obj-C SelRef Protection.

Figure 2: Fusion Set that displays the newly added Obj-C SelRef Protection protection
Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory).

Open the Fusion Set Detail Summary by clicking the “...” symbol on the far-right corner of the Fusion Set. Copy the Fusion Set ID from the Fusion Set Detail Summary (as shown below):

Figure 3: Fusion Set Detail Summary

Follow the instructions below to use the Fusion Set ID inside any standard mobile DevOps or CI/CD toolkit like Bitrise, Jenkins, Travis, Team City, Circle CI or other system:

Refer to the Appdome API Reference Guide for API building instructions.

Look for sample APIs in Appdome’s GitHub Repository.

Add the Obj-C SelRef Protection feature to your security template.

Navigate to Build > Security tab > ONEShield™ section in the Appdome Console.
Like all other options in ONEShield™, Obj-C SelRef Protection is turned on by default, as shown below:
Figure 4: Selecting Obj-C SelRef Protection
Note: The App Compromise Notification contains an easy to follow default remediation path for the mobile app end user. You can customize this message as required to achieve brand specific support, workflow or other messaging.

Toggle On > Obj-C SelRef Protection.

Figure 4: Selecting Protect Obj-C SelRef

Initiate the build command either by clicking Build My App at the bottom of the Build Workflow (shown in Figure 4) or via your CI/CD as described in Section 2.1.4.

Congratulations! The Obj-C SelRef Protection protection is now added to the mobile app

Certify the Obj-C SelRef Protection feature in iOS Apps

After building Obj-C SelRef Protection, Appdome generates a Certified Secure™ certificate to guarantee that the Obj-C SelRef Protection protection has been added and is protecting the app. To verify that the Obj-C SelRef Protection protection has been added to the mobile app, locate the protection in the Certified Secure™ certificate as shown below:

Figure 5: Certified Secure™ certificate

Each Certified Secure™ certificate provides DevOps and DevSecOps organizations the entire workflow summary, audit trail of each build, and proof of protection that Obj-C SelRef Protection has been added to each iOS app. Certified Secure provides instant and in-line DevSecOps compliance certification that Obj-C SelRef Protection and other mobile app security features are in each build of the mobile app.

Using Threat-Events™ for Obj-C SelRef Intelligence and Control in iOS Apps

Appdome Threat-Events™ provides consumable in-app mobile app attack intelligence and defense control when Obj-C SelRef is detected. To consume and use Threat-Events™ for Obj-C SelRef in iOS Apps, use AddObserverForName in Notification Center, and the code samples for Threat-Events™ for Obj-C SelRef shown below.

The specifications and options for Threat-Events™ for Obj-C SelRef are:

Threat-Event™ Elements Protect Obj-C SelRef Method Detail

Appdome Feature Name Obj-C SelRef Protection

Threat-Event Mode

OFF, IN-APP DEFENSE Appdome detects, defends and notifies user (standard OS dialog) using customizable messaging.

ON, IN-APP DETECTION Appdome detects the attack or threat and passes the event in a standard format to the app for processing (app chooses how and when to enforce).

ON, IN-APP DEFENSE Uses Appdome Enforce mode for any attack or threat and passes the event in a standard format to the app for processing (gather intel on attacks and threats without losing any protection).

Certified Secure™ Threat Event Check x

Visible in ThreatScope™ x

Developer Parameters for Protecting Obj-C SelRef Threat-Event™

Threat-Event NAME

Threat-Event DATA reasonData

Threat-Event CODE reasonCode

Threat-Event REF

Threat-Event SCORE
currentThreatEventScore Current Threat-Event score

threatEventsScore Total Threat-events score

Threat-Event Context Keys

message Message displayed for the user on event

failSafeEnforce Timed enforcement against the identified threat

externalID The external ID of the event which can be listened via Threat Events

osVersion OS version of the current device

deviceModel Current device model

deviceManufacturer The manufacturer of the current device

fusedAppToken The task ID of the Appdome fusion of the currently running app

kernelInfo Info about the kernel: system name, node name, release, version and machine.

deviceID Current device ID

reasonCode Reason code of the occurred event

buildDate Appdome fusion date of the current application

devicePlatform OS name of the current device

updatedOSVersion Is the OS version up to date

timeZone Time zone

deviceFaceDown Is the device face down

locationLong Location longitude conditioned by location permission

locationLat Location latitude conditioned by location permission

locationState Location state conditioned by location permission

wifiSsid Wifi SSID

wifiSsidPermissionStatus Wifi SSID permission status

threatCode The last six characters of the threat code specify the OS, allowing the Threat Resolution Center to address the attack on the affected device.

With Threat-Events™ enabled (turned ON), iOS developers can get detailed attack intelligence and granular defense control in iOS applications and create amazing user experiences for all mobile end users when Obj-C SelRef is detected.

The following is a code sample for native iOS apps, which uses all values in the specification above for Obj-C SelRef Protection:

Important! Replace all placeholder instances of <Context Key> with the specific name of your threat event context key across all language examples. This is crucial to ensure your code functions correctly with the intended event data. For example, The <Context Key> could be the message, externalID, OS Version, reason code, etc.

let center = NotificationCenter.default center.addObserver(forName: Notification.Name(""), object: nil, queue: nil) { (note) in guard let usrInf = note.userInfo else { return } let message = usrInf["message"]; // Message shown to the user let reasonData = usrInf["reasonData"]; // Threat detection cause let reasonCode = usrInf["reasonCode"]; // Event reason code // Current threat event score let currentThreatEventScore = usrInf["currentThreatEventScore"]; // Total threat events score let threatEventsScore = usrInf["threatEventsScore"]; // Replace '' with your specific event context key // let variable = usrInf[""]; // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) }

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let center = NotificationCenter.default
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center.addObserver(forName: Notification.Name(""), object: nil, queue: nil) { (note) in
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guard let usrInf = note.userInfo else {
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return
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}
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let message = usrInf["message"]; // Message shown to the user
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let reasonData = usrInf["reasonData"]; // Threat detection cause
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let reasonCode = usrInf["reasonCode"]; // Event reason code
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// Current threat event score
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let currentThreatEventScore = usrInf["currentThreatEventScore"];
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// Total threat events score
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let threatEventsScore = usrInf["threatEventsScore"];
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// Replace '<Context Key>' with your specific event context key
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// let variable = usrInf["<Context Key>"];
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// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
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}

[[NSNotificationCenter defaultCenter] addObserverForName: @"" object:nil queue:nil usingBlock:^(NSNotification *org_note) { __block NSNotification *note = org_note; dispatch_async(dispatch_get_main_queue(), ^(void) { // Message shown to the user NSString *message = [[note userInfo] objectForKey:@"message"]; // Threat detection cause NSString *reasonData = [[note userInfo] objectForKey:@"reasonData"]; // Event reason code NSString *reasonCode = [[note userInfo] objectForKey:@"reasonCode"]; // Current threat event score NSString *currentThreatEventScore = [[note userInfo] objectForKey:@"currentThreatEventScore"]; // Total threat events score NSString *threatEventsScore = [[note userInfo] objectForKey:@"threatEventsScore"]; // Replace '' with your specific event context key // NSString *variable = [[note userInfo] objectForKey:@""]; // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) }); }];

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[[NSNotificationCenter defaultCenter] addObserverForName: @"" object:nil queue:nil usingBlock:^(NSNotification *org_note) {
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__block NSNotification *note = org_note;
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dispatch_async(dispatch_get_main_queue(), ^(void) {
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// Message shown to the user
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NSString *message = [[note userInfo] objectForKey:@"message"];
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// Threat detection cause
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NSString *reasonData = [[note userInfo] objectForKey:@"reasonData"];
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// Event reason code
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NSString *reasonCode = [[note userInfo] objectForKey:@"reasonCode"];
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// Current threat event score
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NSString *currentThreatEventScore = [[note userInfo] objectForKey:@"currentThreatEventScore"];
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// Total threat events score
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NSString *threatEventsScore = [[note userInfo] objectForKey:@"threatEventsScore"];
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// Replace '<Context Key>' with your specific event context key
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// NSString *variable = [[note userInfo] objectForKey:@"<Context Key>"];
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// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
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});
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}];

const { ADDevEvents } = NativeModules; const aDDevEvents = new NativeEventEmitter(ADDevEvents); function registerToDevEvent(action, callback) { NativeModules.ADDevEvents.registerForDevEvent(action); aDDevEvents.addListener(action, callback); } export function registerToAllEvents() { registerToDevEvent( "", (userinfo) => Alert.alert(JSON.stringify(userinfo)) var message = userinfo["message"] // Message shown to the user var reasonData = userinfo["reasonData"] // Threat detection cause var reasonCode = userinfo["reasonCode"] // Event reason code // Current threat event score var currentThreatEventScore = userinfo["currentThreatEventScore"] // Total threat events score var threatEventsScore = userinfo["threatEventsScore"] // Replace '' with your specific event context key // var variable = userinfo[""] // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) ); }

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const { ADDevEvents } = NativeModules;
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const aDDevEvents = new NativeEventEmitter(ADDevEvents);
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function registerToDevEvent(action, callback) {
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NativeModules.ADDevEvents.registerForDevEvent(action);
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aDDevEvents.addListener(action, callback);
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}
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export function registerToAllEvents() {
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registerToDevEvent(
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"",
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(userinfo) => Alert.alert(JSON.stringify(userinfo))
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var message = userinfo["message"] // Message shown to the user
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var reasonData = userinfo["reasonData"] // Threat detection cause
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var reasonCode = userinfo["reasonCode"] // Event reason code
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// Current threat event score
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var currentThreatEventScore = userinfo["currentThreatEventScore"]
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// Total threat events score
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var threatEventsScore = userinfo["threatEventsScore"]
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// Replace '<Context Key>' with your specific event context key
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// var variable = userinfo["<Context Key>"]
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// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
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);
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}

RegisterReceiver(new ThreatEventReceiver(), new IntentFilter("")); class ThreatEventReceiver : BroadcastReceiver { public override void OnReceive(Context context, Intent intent) { String message = intent.GetStringExtra("message"); // Message shown to the user String reasonData = intent.GetStringExtra("reasonData"); // Threat detection cause String reasonCode = intent.GetStringExtra("reasonCode"); // Event reason code // Current threat event score String currentThreatEventScore = intent.GetStringExtra("currentThreatEventScore"); // Total threat events score String threatEventsScore = intent.GetStringExtra("threatEventsScore"); // Replace '' with your specific event context key // String variable = intent.GetStringExtra(""); // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) } }

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RegisterReceiver(new ThreatEventReceiver(), new IntentFilter(""));
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class ThreatEventReceiver : BroadcastReceiver
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{
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public override void OnReceive(Context context, Intent intent)
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{
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// Message shown to the user
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String message = intent.GetStringExtra("message");
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// Threat detection cause
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String reasonData = intent.GetStringExtra("reasonData");
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// Event reason code
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String reasonCode = intent.GetStringExtra("reasonCode");
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// Current threat event score
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String currentThreatEventScore = intent.GetStringExtra("currentThreatEventScore");
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// Total threat events score
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String threatEventsScore = intent.GetStringExtra("threatEventsScore");
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// Replace '<Context Key>' with your specific event context key
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// String variable = intent.GetStringExtra("<Context Key>");
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// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
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}
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}

NSNotificationCenter.DefaultCenter.AddObserver( (NSString)"", // Threat-Event Identifier delegate (NSNotification notification) { // Message shown to the user var message = notification.UserInfo.ObjectForKey("message"); // Threat detection cause var reasonData = notification.UserInfo.ObjectForKey("reasonData"); // Event reason code var reasonCode = notification.UserInfo.ObjectForKey("reasonCode"); // Current threat event score var currentThreatEventScore = notification.UserInfo.ObjectForKey("currentThreatEventScore"); // Total threat events score var threatEventsScore = notification.UserInfo.ObjectForKey("threatEventsScore"); // Replace '' with your specific event context key // var variable = notification.UserInfo.ObjectForKey(""); // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) } );

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NSNotificationCenter.DefaultCenter.AddObserver(
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(NSString)"", // Threat-Event Identifier
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delegate (NSNotification notification)
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{
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// Message shown to the user
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var message = notification.UserInfo.ObjectForKey("message");
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// Threat detection cause
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var reasonData = notification.UserInfo.ObjectForKey("reasonData");
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// Event reason code
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var reasonCode = notification.UserInfo.ObjectForKey("reasonCode");
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// Current threat event score
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var currentThreatEventScore = notification.UserInfo.ObjectForKey("currentThreatEventScore");
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// Total threat events score
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var threatEventsScore = notification.UserInfo.ObjectForKey("threatEventsScore");
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// Replace '<Context Key>' with your specific event context key
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// var variable = notification.UserInfo.ObjectForKey("<Context Keys>");
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// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
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}
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);

window.broadcaster.addEventListener("", function(userInfo) { var message = userInfo.message // Message shown to the user var reasonData = userInfo.reasonData // Threat detection cause var reasonCode = userInfo.reasonCode // Event reason code // Current threat event score var currentThreatEventScore = userInfo.currentThreatEventScore // Total threat events score var threatEventsScore = userInfo.threatEventsScore // Replace '' with your specific event context key // var variable = userInfo. // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) });

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window.broadcaster.addEventListener("", function(userInfo) {
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var message = userInfo.message // Message shown to the user
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var reasonData = userInfo.reasonData // Threat detection cause
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var reasonCode = userInfo.reasonCode // Event reason code
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// Current threat event score
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var currentThreatEventScore = userInfo.currentThreatEventScore
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// Total threat events score
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var threatEventsScore = userInfo.threatEventsScore
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// Replace '<Context Key>' with your specific event context key
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// var variable = userInfo.<Context Keys>
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// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
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});

import 'dart:async'; import 'package:flutter/material.dart'; import 'package:flutter/services.dart'; class PlatformChannel extends StatefulWidget { const PlatformChannel({super.key}); @override State createState() => _PlatformChannelState(); } class _PlatformChannelState extends State { // Replace with your EventChannel name static const String _eventChannelName = ""; static const EventChannel _eventChannel = EventChannel(_eventChannelName); @override void initState() { super.initState(); _eventChannel.receiveBroadcastStream().listen(_onEvent, onError: _onError); } void _onEvent(Object? event) { setState(() { // Adapt this section based on your specific event data structure var eventData = event as Map; // Example: Accessing 'externalID' field from the event var externalID = eventData['externalID']; // Customize the rest of the fields based on your event structure String message = eventData['message']; // Message shown to the user String reasonData = eventData['reasonData']; // Threat detection cause String reasonCode = eventData['reasonCode']; // Event reason code // Current threat event score String currentThreatEventScore = eventData['currentThreatEventScore']; // Total threat events score String threatEventsScore = eventData['threatEventsScore']; // Replace '' with your specific event context key // String variable = eventData['']; }); } // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) }

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import 'dart:async';
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import 'package:flutter/material.dart';
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import 'package:flutter/services.dart';
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class PlatformChannel extends StatefulWidget {
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const PlatformChannel({super.key});
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@override
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State<PlatformChannel> createState() => _PlatformChannelState();
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}
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class _PlatformChannelState extends State<PlatformChannel> {
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// Replace with your EventChannel name
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static const String _eventChannelName = "";
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static const EventChannel _eventChannel = EventChannel(_eventChannelName);
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@override
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void initState() {
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super.initState();
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_eventChannel.receiveBroadcastStream().listen(_onEvent, onError: _onError);
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}
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void _onEvent(Object? event) {
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setState(() {
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// Adapt this section based on your specific event data structure
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var eventData = event as Map;
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// Example: Accessing 'externalID' field from the event
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var externalID = eventData['externalID'];
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// Customize the rest of the fields based on your event structure
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String message = eventData['message']; // Message shown to the user
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String reasonData = eventData['reasonData']; // Threat detection cause
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String reasonCode = eventData['reasonCode']; // Event reason code
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// Current threat event score
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String currentThreatEventScore = eventData['currentThreatEventScore'];
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// Total threat events score
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String threatEventsScore = eventData['threatEventsScore'];
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// Replace '<Context Key>' with your specific event context key
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// String variable = eventData['<Context Keys>'];
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});
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}
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// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
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}

Using Appdome, there are no development or coding prerequisites to build secured iOS Apps by using Obj-C SelRef Protection. There is no SDK and no library to code or implement in the app and no gateway to deploy in your network. All protections are built into each app and the resulting app is self-defending and self-protecting.

Releasing and Publishing Mobile Apps with Obj-C SelRef Protection

After successfully securing your app by using Appdome, there are several available options to complete your project, depending on your app lifecycle or workflow. These include:

Customizing, Configuring & Branding Secure Mobile Apps.

Deploying/Publishing Secure mobile apps to Public or Private app stores.

Releasing Secured Android & iOS Apps built on Appdome.

Related Articles:

How to Prevent Code Tampering in Android Apps

How to Prevent Code Tampering in iOS Apps

How to Automatically Validate Android and iOS App Logic & File Structure in CI/CD

How to Obfuscate Security Features on Appdome

How Do I Learn More?

If you have any questions, please send them our way at support.appdome.com or via the chat window on the Appdome platform.

Thank you!

Thanks for visiting Appdome! Our mission is to secure every app on the planet by making mobile app security easy. We hope we’re living up to the mission with your project.

How to Protect Obj-C SelRefs Against Tampering Apps Using AI

What Are Objective-C SelRefs in iOS Apps?

How Appdome Protects Objective-C SelRefs Against Tampering?

Prerequisites for Using Appdome's Obj-C SelRef Protection Plugins:

How to Implement Protect Obj-C SelRef in iOS Apps Using Appdome

Designate the Mobile App to be protected.

Upload an app via the Appdome Mobile Defense platform GUI or via Appdome’s DEV-API or CI/CD Plugins.

Select the defense: Obj-C SelRef Protection.

Add the Obj-C SelRef Protection feature to your security template.

Certify the Obj-C SelRef Protection feature in iOS Apps

Using Threat-Events™ for Obj-C SelRef Intelligence and Control in iOS Apps

Related Articles:

How Do I Learn More?

Thank you!

Threat-Event™ Elements	Protect Obj-C SelRef Method Detail
Appdome Feature Name	Obj-C SelRef Protection
Threat-Event Mode
OFF, IN-APP DEFENSE	Appdome detects, defends and notifies user (standard OS dialog) using customizable messaging.
ON, IN-APP DETECTION	Appdome detects the attack or threat and passes the event in a standard format to the app for processing (app chooses how and when to enforce).
ON, IN-APP DEFENSE	Uses Appdome Enforce mode for any attack or threat and passes the event in a standard format to the app for processing (gather intel on attacks and threats without losing any protection).
Certified Secure™ Threat Event Check	x
Visible in ThreatScope™	x
Developer Parameters for Protecting Obj-C SelRef Threat-Event™
Threat-Event NAME
Threat-Event DATA	reasonData
Threat-Event CODE	reasonCode
Threat-Event REF
Threat-Event SCORE
currentThreatEventScore	Current Threat-Event score
threatEventsScore	Total Threat-events score

Threat-Event Context Keys
message	Message displayed for the user on event
failSafeEnforce	Timed enforcement against the identified threat
externalID	The external ID of the event which can be listened via Threat Events
osVersion	OS version of the current device
deviceModel	Current device model
deviceManufacturer	The manufacturer of the current device
fusedAppToken	The task ID of the Appdome fusion of the currently running app
kernelInfo	Info about the kernel: system name, node name, release, version and machine.
deviceID	Current device ID
reasonCode	Reason code of the occurred event
buildDate	Appdome fusion date of the current application
devicePlatform	OS name of the current device
updatedOSVersion	Is the OS version up to date
timeZone	Time zone
deviceFaceDown	Is the device face down
locationLong	Location longitude conditioned by location permission
locationLat	Location latitude conditioned by location permission
locationState	Location state conditioned by location permission
wifiSsid	Wifi SSID
wifiSsidPermissionStatus	Wifi SSID permission status
threatCode	The last six characters of the threat code specify the OS, allowing the Threat Resolution Center to address the attack on the affected device.