EventSource is a Swift package that provides a simple implementation of a client for Server-Sent Events (SSE). It allows you to easily receive real-time updates from a server over a persistent HTTP connection, using a simple and efficient interface.
It also leverages Swift concurrency features to provide a more expressive and intuitive way to handle asynchronous operations.
Note
Please note that this package was originally developed to be used in conjunction with another package, and as such, it may not cover all specification details. Please be aware of this limitation when evaluating whether EventSource is suitable for your specific use case.
- Simple Swift API for SSE
- Supports data-only mode
- Data race safety with Swift 6
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
From Xcode menu: File > Swift Packages > Add Package Dependency
https://github.com/Recouse/EventSource
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"), ]),
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.
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) }
- macOS 10.15+
- iOS 13.0+
- tvOS 13.0+
- watchOS 6.0+
- visionOS 1.0+
No dependencies.
Contributions to are always welcomed! For more details see CONTRIBUTING.md.
- Mutex backport from swift-sharing
EventSource is released under the MIT License. See LICENSE for more information.