Websockets in swift for iOS and OSX



Starscream is a conforming WebSocket (RFC 6455) client library in Swift for iOS and OSX.

It's Objective-C counter part can be found here: Jetfire

This is written Swift 2. (the latest). If you need older legecy support checkout the Swift-1.2 branch here.


  • Conforms to all of the base Autobahn test suite.
  • Nonblocking. Everything happens in the background, thanks to GCD.
  • Simple delegate pattern design.
  • TLS/WSS support.
  • Simple concise codebase at just a few hundred LOC.


First thing is to import the framework. See the Installation instructions on how to add the framework to your project.

import Starscream

Once imported, you can open a connection to your WebSocket server. Note that socket is probably best as a property, so your delegate can stick around.

var socket = WebSocket(url: NSURL(string: "ws://localhost:8080/")!)
socket.delegate = self

After you are connected, there are some delegate methods that we need to implement.


websocketDidConnect is called as soon as the client connects to the server.

func websocketDidConnect(socket: WebSocket) {
    println("websocket is connected")


websocketDidDisconnect is called as soon as the client is disconnected from the server.

func websocketDidDisconnect(socket: WebSocket, error: NSError?) {
    println("websocket is disconnected: \(error?.localizedDescription)")


websocketDidReceiveMessage is called when the client gets a text frame from the connection.

func websocketDidReceiveMessage(socket: WebSocket, text: String) {
    println("got some text: \(text)")


websocketDidReceiveData is called when the client gets a binary frame from the connection.

func websocketDidReceiveData(socket: WebSocket, data: NSData) {
    println("got some data: \(data.length)")

Optional: websocketDidReceivePong (required protocol: WebSocketPongDelegate)

websocketDidReceivePong is called when the client gets a pong response from the connection. You need to implement the WebSocketPongDelegate protocol and set an additional delegate, eg: socket.pongDelegate = self

func websocketDidReceivePong(socket: WebSocket) {
    println("Got pong!")

Or you can use closures.

var socket = WebSocket(url: NSURL(string: "ws://localhost:8080/")!)
socket.onConnect = {
    println("websocket is connected")
socket.onDisconnect = { (error: NSError?) in
    println("websocket is disconnected: \(error?.localizedDescription)")
socket.onText = { (text: String) in
    println("got some text: \(text)")
socket.onData = { (data: NSData) in
    println("got some data: \(data.length)")
//you could do onPong as well.

The delegate methods give you a simple way to handle data from the server, but how do you send data?


The writeData method gives you a simple way to send NSData (binary) data to the server.

self.socket.writeData(data) //write some NSData over the socket!


The writeString method is the same as writeData, but sends text/string.

self.socket.writeString("Hi Server!") //example on how to write text over the socket!


The writePing method is the same as writeData, but sends a ping control frame.

self.socket.writePing(NSData()) //example on how to write a ping control frame over the socket!


The disconnect method does what you would expect and closes the socket.



Returns if the socket is connected or not.

if self.socket.isConnected {
  // do cool stuff.

Custom Headers

You can also override the default websocket headers with your own custom ones like so:

socket.headers["Sec-WebSocket-Protocol"] = "someother protocols"
socket.headers["Sec-WebSocket-Version"] = "14"
socket.headers["My-Awesome-Header"] = "Everything is Awesome!"


If you need to specify a protocol, simple add it to the init:

//chat and superchat are the example protocols here
var socket = WebSocket(url: NSURL(string: "ws://localhost:8080/")!, protocols: ["chat","superchat"])
socket.delegate = self

Self Signed SSL and VOIP

There are a couple of other properties that modify the stream:

var socket = WebSocket(url: NSURL(string: "ws://localhost:8080/")!, protocols: ["chat","superchat"])

//set this if you are planning on using the socket in a VOIP background setting (using the background VOIP service).
socket.voipEnabled = true

//set this you want to ignore SSL cert validation, so a self signed SSL certificate can be used.
socket.selfSignedSSL = true

SSL Pinning

SSL Pinning is also supported in Starscream.

var socket = WebSocket(url: NSURL(string: "ws://localhost:8080/")!, protocols: ["chat","superchat"])
let data = ... //load your certificate from disk = SSLSecurity(certs: [SSLCert(data: data)], usePublicKeys: true)
// = SSLSecurity() //uses the .cer files in your app's bundle

You load either a NSData blob of your certificate or you can use a SecKeyRef if you have a public key you want to use. The usePublicKeys bool is whether to use the certificates for validation or the public keys. The public keys will be extracted from the certificates automatically if usePublicKeys is choosen.

Custom Queue

A custom queue can be specified when delegate methods are called. By default dispatch_get_main_queue is used, thus making all delegate methods calls run on the main thread. It is important to note that all WebSocket processing is done on a background thread, only the delegate method calls are changed when modifying the queue. The actual processing is always on a background thread and will not pause your app.

var socket = WebSocket(url: NSURL(string: "ws://localhost:8080/")!, protocols: ["chat","superchat"])
//create a custom queue
socket.queue = dispatch_queue_create("com.vluxe.starscream.myapp", nil)

Example Project

Check out the SimpleTest project in the examples directory to see how to setup a simple connection to a WebSocket server.


Starscream works with iOS 7/OSX 10.9 or above. It is recommended to use iOS 8/10.10 or above for Cocoapods/framework support. To use Starscream with a project targeting iOS 7, you must include all Swift files directly in your project.



Check out Get Started tab on

To use Starscream in your project add the following 'Podfile' to your project

source ''
platform :ios, '8.0'

pod 'Starscream', '~> 1.0.0'

Then run:

pod install


Check out the Carthage docs on how to add a install. The Starscream framework is already setup with shared schemes.

Carthage Install

You can install Carthage with Homebrew using the following command:

$ brew update
$ brew install carthage

To integrate Starscream into your Xcode project using Carthage, specify it in your Cartfile:

github "daltoniam/Starscream" >= 1.0.0


First see the installation docs for how to install Rogue.

To install Starscream run the command below in the directory you created the rogue file.

rogue add

Next open the libs folder and add the Starscream.xcodeproj to your Xcode project. Once that is complete, in your "Build Phases" add the Starscream.framework to your "Link Binary with Libraries" phase. Make sure to add the libs folder to your .gitignore file.


Simply grab the framework (either via git submodule or another package manager).

Add the Starscream.xcodeproj to your Xcode project. Once that is complete, in your "Build Phases" add the Starscream.framework to your "Link Binary with Libraries" phase.

Add Copy Frameworks Phase

If you are running this in an OSX app or on a physical iOS device you will need to make sure you add the Starscream.framework to be included in your app bundle. To do this, in Xcode, navigate to the target configuration window by clicking on the blue project icon, and selecting the application target under the "Targets" heading in the sidebar. In the tab bar at the top of that window, open the "Build Phases" panel. Expand the "Link Binary with Libraries" group, and add Starscream.framework. Click on the + button at the top left of the panel and select "New Copy Files Phase". Rename this new phase to "Copy Frameworks", set the "Destination" to "Frameworks", and add Starscream.framework respectively.


  • WatchOS
  • Add Unit Tests


Starscream is licensed under the Apache v2 License.


Dalton Cherry

Austin Cherry