SwiftUseCase

SwiftUseCase is library for creating independent & test coverable usecases with a powerfull execution api.

Installation

You can use Swift Package Manager to integrate the library by adding the following dependency in your Package.swift file or by adding directly within Xcode:

.package(url: "https://github.com/xtro/SwiftUseCase.git", .upToNextMajor(from: "0.0.1"))

Definitions

A UseCase is a simple container that contains a Parameter and Result type and executing an Execution.

public protocol UseCaseable {
    associatedtype Parameter: Sendable
    associatedtype Result: Sendable
    associatedtype Execution: Sendable
    var execute: Execution { get }
}

There are four types of executions:

public typealias Executable<Parameter: Sendable, Result: Sendable> = @Sendable (Parameter) -> Result
public typealias AsyncExecutable<Parameter: Sendable, Result: Sendable> = @Sendable (Parameter) async -> Result
public typealias ThrowingExecutable<Parameter: Sendable, Result: Sendable> = @Sendable (Parameter) throws -> Result
public typealias AsyncThrowingExecutable<Parameter: Sendable, Result: Sendable> = @Sendable (Parameter) async throws -> Result

Getting started

In this example we implement a data task using swift concurrency. The parameters are an URLRequest and an URLSession:

import SwiftUseCase

public enum Network {
    public struct DataTask: AsyncThrowingUseCase {
        public struct Parameter {
            let request: URLRequest
            let session: URLSession
        }
        public typealias Result = (response: HTTPURLResponse, data: Data)
        
        public var execute: AsyncThrowingExecutable<Parameter, Result> = { parameter in
            class CancellableWrapper {
                var dataTask: URLSessionDataTask?
            }
            let urlSessionTask = CancellableWrapper()
            return try await withTaskCancellationHandler {
                return try await withUnsafeThrowingContinuation { continuation in
                    urlSessionTask.dataTask = parameter.session.dataTask(with: parameter.request) { data, response, error in
                        if let error = error {
                            continuation.resume(throwing: error)
                        }
                        if let data = data {
                            let result = (response as! HTTPURLResponse, data)
                            continuation.resume(returning: result)
                        }
                    }
                    urlSessionTask.dataTask?.resume()
                }
            } onCancel: {
                urlSessionTask.dataTask?.cancel()
            }
        }
    }
}

After that we can use the implemented code in many ways.

Use as a combine publisher:

let usecase = Network.DataTask()
usecase.publisher(
    .init(
        request: URLRequest(url: URL(string: path)!),
        session: session ?? .shared
    )
)

It looks nice, but the parameter and initialization is too complex in this case, we can reduce it by writing an extension like this:

extension Network.DataTask.Parameter {
    static func get(_ path: String, session: URLSession? = nil) -> Self {
        .init(
            request: URLRequest(url: URL(string: path)!),
            session: session ?? .shared
        )
    }
}
extension Network {
    static var dataTask: DataTask {
        DataTask()
    }
}

much better, now we can use as a Combine publisher:

Network.dataTask
    .publisher( .get("https://api.coincap.io/v2/assets") )
    ...

or using blocks:

Network.dataTask( .get("https://api.coincap.io/v2/assets") ) { result in
   ...
}

or in swift concurrency:

let result = try await Network.dataTask( .get("https://api.coincap.io/v2/assets") )

finally every UseCase is convertable to AnyUseCase a type-erased representation of a usecase:

let usecase = MyUseCase().eraseToAnyUseCase
usecase.onComplete = {
    print("Result: \($0)")
}
usecase.onFailure = {
    print("Failure: \($0)")
}
usecase(parameter)

Sponsors

SwiftUseCase is an MIT-licensed open source project with its ongoing development made possible entirely by the support of awesome backers. If you'd like to join them, please consider sponsoring this development.

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

License

This library is released under the MIT license. See LICENSE for details.