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Using Twilio Voice side by side with WebRTC - iOS

Twilio's Programmable Voice SDK for iOS is based upon a fork of the Chromium WebRTC project ( This heritage usually presents an interesting challenge of class conflicts when using other WebRTC dependencies alongside Twilio in your iOS application. We have designed Voice SDK 3.x and above to work alongside other libraries that also inherit from webrtc. However, in the case you run into conflict issues, follow this guide for ways how to resolve conflicts.

How do conflicts occur?

Objective-C does not support the concept of namespaces. Instead, developers typically use a 3-4 letter prefix to uniquely identify their classes. WebRTC classes are prefixed with RTC, while Twilio Voice classes are prefixed with TVO.

Consider the following Podfile which consumes both Twilio Voice and WebRTC:

source ''

target 'TARGET_NAME' do
  platform :ios, '10.0'
  pod 'TwilioVoice', '4.0.0'
  pod 'GoogleWebRTC'

Some classes with the RTC prefix are present both in WebRTC (publicly) and in Twilio Voice (privately). When classes are loaded by the Objective-C runtime, any conflicts which occur are raised in your console logs:

Console log showing that several libraries are implemented twice

You can see that classes like RTCAudioSession are provided by both libraries. When classes conflict at runtime, the version which is loaded is undefined. This could result in unexpected behavior or crashes in your application.

How do I resolve class conflicts?

One technique used to resolve class conflicts is to rename (prefix) the impacted classes. As of version 4.0.0, Twilio Voice now prefixes RTC classes with TVO. For example, RTCAudioSession now becomes TVORTCAudioSession.

If you wish to use Twilio Voice side by side with other WebRTC dependencies we recommend that you update to 4.x to eliminate class conflicts.

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Need some help?

We all do sometimes; code is hard. Get help now from our support team, or lean on the wisdom of the crowd by visiting Twilio's Stack Overflow Collective or browsing the Twilio tag on Stack Overflow.

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