Obfuscate iOS Control Flows & Methods, Anti-Reversing iOS Apps

Last updated November 29, 2023 by Appdome

Learn to Obfuscate code and control flows in iOS apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

What are Code and Control Flows?

Control flow is the order by which function calls, instructions, and statements are executed or evaluated when running a program. The control flow is a significant part of the logic of any computer program, as its implementation means that rather than just running any line of code sequentially, the developer determines what section of code is run in a program at any time. This allows implementing decision making, looping, and branching, so that specific blocks of code are executed only if they meet one or more conditions.

Code flow describes the path your code follows from starting point to a destination (final) point, in order to obtain the requested output. For example: getting a search query from a user, looking up the requested item in a list or a database, and displaying the search results.

Why do I Need to Obfuscate the Code and Control Flows?

Decompilers have reached a maturity level that allows recovering source code back from mobile apps with ease. Obfuscation is an established, widely used preventive measure against static reverse engineering attempts. Obfuscation proved to be an high performing, easy to use solution.

Appdome’s Flow Relocation modifies a mobile app’s compiled code by relocating and obfuscating the app’s code flow and logical control-flow. In so doing, Appdome makes reverse engineering much harder to perform while preserving the functionality and performance of the original app.

Prerequisites for Using Flow Relocation:

To use Appdome’s mobile app security build system to Obfuscate code and control flows , you’ll need:

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

Obfuscate code and control flows on iOS apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending iOS Apps that Obfuscate code and control flows without an SDK or gateway:

Upload the Mobile App to Appdome.
1. Upload an app to Appdome’s Mobile App Security Build System
2. Upload Method: Appdome Console or DEV-API
3. iOS Formats: .ipa
4. Flow Relocation Compatible With: Obj-C, Java, Swift, Flutter, React Native, Unity, Xamarin, Cordova and more
Build the feature: Flow Relocation.
1. Building Flow Relocation by using Appdome’s DEV-API:
  1. Create and name the Fusion Set (security template) that will contain the Flow Relocation feature as shown below:
  2. Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the Flow Relocation feature via Appdome Console, to add the Flow Relocation feature to this Fusion Set.
  3. 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 2: Fusion Set Detail Summary
    Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory).
  4. Follow the instructions below to use the Fusion Set ID inside any standard mobile DevOps or CI/CD toolkit like Bitrise, App Center, Jenkins, Travis, Team City, Circle CI or other system:
    
    Build an API for the app – for instructions, see the tasks under Appdome API Reference Guide
    
    Look for sample APIs in Appdome’s GitHub Repository
2. Building the Flow Relocation feature via Appdome Console
  
  To build the Flow Relocation protection by using Appdome Console, follow the instructions below.
  1. Where: Inside the Appdome Console, go to Build > Security Tab > TOTALCode™ Obfuscation section.
    Like all other options in ONEShield™, Flow Relocation is turned on by default, as shown below:
    Figure 3: Flow Relocation option
    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.
  2. When you select the Flow Relocation you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Flow Relocation
    
    Figure 4: Fusion Set that displays the newly added Flow Relocation protection
  3. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
Congratulations! The Flow Relocation protection is now added to the mobile app
Certify the Flow Relocation feature in iOS Apps

After building Flow Relocation, Appdome generates a Certified Secure™ certificate to guarantee that the Flow Relocation protection has been added and is protecting the app. To verify that the Flow Relocation 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 Flow Relocation has been added to each iOS app. Certified Secure provides instant and in-line DevSecOps compliance certification that Flow Relocation and other mobile app security features are in each build of the mobile app

Using Threat-Events™ for code and control flows Intelligence and Control in iOS Apps

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

The specifications and options for Threat-Events™ for code and control flows are:

Threat-Event™ Elements	Obfuscate code and control flows Method Detail
Appdome Feature Name	Flow Relocation
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 Obfuscating code and control flows 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

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 code and control flows are detected.

The following is a code sample for native iOS apps, which uses all values in the specification above for Flow Relocation:

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...)
                    }

x
 
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 '<Context Key>' with your specific event context key
    // let variable = usrInf["<Context Key>"];
​
    // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
}

                    [[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...)
                        });
                    }];

xxxxxxxxxx
 
[[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 '<Context Key>' with your specific event context key
        // NSString *variable = [[note userInfo] objectForKey:@"<Context Key>"];
​
        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
    });
}];

                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...)
                    );
                }

xxxxxxxxxx
 
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 '<Context Key>' with your specific event context key
        // var variable = userinfo["<Context Key>"]
​
        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
    );
}

                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...)
                    }
                }

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

                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...)
                    }
                );

x
 
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 '<Context Key>' with your specific event context key
        // var variable = notification.UserInfo.ObjectForKey("<Context Keys>");
​
        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
    }
);

                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...)
                });

xxxxxxxxxx
 
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 '<Context Key>' with your specific event context key
    // var variable = userInfo.<Context Keys>
​
    // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
});

                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...)
                }

x
 
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
​
class PlatformChannel extends StatefulWidget {
    const PlatformChannel({super.key});
​
    @override
    State<PlatformChannel> createState() => _PlatformChannelState();
}
​
class _PlatformChannelState extends State<PlatformChannel> {
    // 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 '<Context Key>' with your specific event context key
            // String variable = eventData['<Context Keys>'];
        });
    }
​
    // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
}

Using Appdome, there are no development or coding prerequisites to build secured iOS Apps by using Flow Relocation. 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 Flow Relocation

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.

How to Obfuscate Non-Native Android & iOS Code and Frameworks

How to add Native Code Obfuscation to any iOS, Android app

How to Encrypt Java Class Files (.dex) in Android Apps

Appdome ONEShield Mobile App Hardening

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.

Obfuscate iOS Control Flows & Methods, Anti-Reversing iOS Apps

What are Code and Control Flows?

Why do I Need to Obfuscate the Code and Control Flows?

Prerequisites for Using Flow Relocation:

Obfuscate code and control flows on iOS apps using Appdome

Upload the Mobile App to Appdome.

Upload an app to Appdome’s Mobile App Security Build System

Build the feature: Flow Relocation.

Building Flow Relocation by using Appdome’s DEV-API:

Building the Flow Relocation feature via Appdome Console

Certify the Flow Relocation feature in iOS Apps

Using Threat-Events™ for code and control flows Intelligence and Control in iOS Apps

Related Articles:

How Do I Learn More?

Thank you!

Supercharge the Experience in Mobile App Defense

Better User Experience in Mobile Defense

Shifting Dynamics in Mobile Fraud Prevention: A Call for Developer Responsibility

Eliminating Information Asymmetry in the Attack Chain With GenAI