Does Swift support WebRTC?
Webrtc comes with Objective C interface. I dont think they will move to swift interface anytime soon. But You can always use them via bridging headers. I have written apprtc (webrtc's demo) in swift 2.3 version with help of bridging headers in github link with a description in this blog . I have planned to write 3.0 version and a swift wrappers over it.
UPDATE The easiest way is to get webRTC in your project is to simply install the CocoaPod using the directions at https://cocoapods.org/pods/WebRTC
If you have never used CocoaPods before you will need to first follow this guide: https://guides.cocoapods.org/using/getting-started.html
The simple answer to the question is that there are currently no open source libraries written in Swift conforming to the WebRTC protocol. You can still compile the code from the official WebRTC project into your app. Directions which may not lead to a successful build can be found here: https://webrtc.org/native-code/ios/
Finally, to clarify Omkar Guhilot's answer: Skylink is a company with a closed source SDK that is designed to work only with their paid stun-turn service, and https://github.com/alongubkin/phonertc requires cordova, which may not be ideal for many native ios developers.
Current version of webrtc framework doesn't require any pods or any extra bridging headers.
The framework can be generated by following instructions on this Link : https://webrtc.github.io/webrtc-org/native-code/ios/
If you follow them correctly you will generate a framework add that framework in your project and follow the webrtc necessary steps and you will have a WEBRTC integrated project.
To know what all steps are necessary follow this link from appear.in : https://tech.appear.in/2015/05/25/Getting-started-with-WebRTC-on-iOS/
This will get you to a stage where you will be able to make calls between a browser and any iOS 8+ device