recouse/eventsource

Features

• [x] Simple Swift API for SSE
• [x] Supports data-only mode
• [x] Data race safety with Swift 6

Installation

The module name of the package is EventSource. Choose one of the instructions below to install and add the following import statement to your source code.

import EventSource

Xcode Package Dependency

From Xcode menu: File > Swift Packages > Add Package Dependency

https://github.com/Recouse/EventSource

Swift Package Manager

In your Package.swift file, first add the following to the package dependencies:

.package(url: "https://github.com/Recouse/EventSource.git"),

And then, include "EventSource" as a dependency for your target:

.target(name: "<target>", dependencies: [
    .product(name: "EventSource", package: "EventSource"),
]),

Usage

Using EventSource is easy. Simply create a new data task from an instance of EventSource with the URLRequest of the SSE endpoint you want to connect to, and await for events:

import EventSource

let task = Task {
    let eventSource = EventSource()
    let dataTask = eventSource.dataTask(for: urlRequest)
    
    for await event in dataTask.events() {
        switch event {
        case .open:
            print("Connection was opened.")
        case .error(let error):
            print("Received an error:", error.localizedDescription)
        case .event(let event):
            print("Received an event", event.data ?? "")
        case .closed:
            print("Connection was closed.")
        }
    }
}

Use task.cancel() to explicitly close the connection. However, in that case .closed event won't be emitted.

Data-only mode

EventSource can be used in data-only mode, making it suitable for popular APIs like OpenAI. Below is an example using OpenAI's completions API:

Task {
    var urlRequest = URLRequest(url: URL(string: "https://api.openai.com/v1/chat/completions")!)
    urlRequest.allHTTPHeaderFields = [
        "Content-Type": "application/json",
        "Authorization": "Bearer \(accessToken)"
    ]
    urlRequest.httpMethod = "POST"
    urlRequest.httpBody = """
    {
        "model": "gpt-4o-mini",
        "messages": [
            {"role": "user", "content": "Why is the sky blue?"}
        ],
        "stream": true
    }
    """.data(using: .utf8)!
    
    let eventSource = EventSource(mode: .dataOnly)
    let dataTask = eventSource.dataTask(for: urlRequest)
    
    var response: String = ""
    
    for await event in dataTask.events() {
        switch event {
        case .event(let event):
            if let data = eventDevent.data?.data(using: .utf8) {
                let chunk = try? JSONDecoder().decode(ChatCompletionChunk.self, from: data)
                let string = chunk?.choices.first?.delta.content ?? ""
                response += string
            }
        default:
            break
        }
    }
    
    print(response)
}

Compatibility

• macOS 10.15+
• iOS 13.0+
• tvOS 13.0+
• watchOS 6.0+
• visionOS 1.0+

Dependencies

No dependencies.

Contributing

Contributions to are always welcomed! For more details see CONTRIBUTING.md.

Credits

• Mutex backport from swift-sharing

License

EventSource is released under the MIT License. See LICENSE for more information.

Package Metadata

Repository: recouse/eventsource

Default branch: main

README: README.md