Moya – Network abstraction layer written in Swift

You’re a smart developer. You probably use Alamofire to abstract away access to URLSession and all those nasty details you don’t really care about. But then, like lots of smart developers, you write ad hoc network abstraction layers. They are probably called “APIManager” or “NetworkModel”, and they always end in tears.

Ad hoc network layers are common in iOS apps. They’re bad for a few reasons:

• Makes it hard to write new apps (“where do I begin?”)
• Makes it hard to maintain existing apps (“oh my god, this mess…”)
• Makes it hard to write unit tests (“how do I do this again?”)

So the basic idea of Moya is that we want some network abstraction layer that sufficiently encapsulates actually calling Alamofire directly. It should be simple enough that common things are easy, but comprehensive enough that complicated things are also easy.

If you use Alamofire to abstract away URLSession, why not use something to abstract away the nitty gritty of URLs, parameters, etc?

Some awesome features of Moya:

• Compile-time checking for correct API endpoint accesses.
• Lets you define a clear usage of different endpoints with associated enum values.
• Treats test stubs as first-class citizens so unit testing is super-easy.

You can check out more about the project direction in the vision document.

Sample Projects

We have provided two sample projects in the repository. To use it download the repo, run carthage update to download the required libraries and open Moya.xcodeproj. You’ll see two schemes: Basic and Multi-Target – select one and then build & run! Source files for these are in the Examples directory in project navigator. Have fun!

Project Status

This project is actively under development, and is being used in Artsy’s auction app. We consider it ready for production use.

Moya Usage

After some setup, using Moya is really simple. You can access an API like this:

provider = MoyaProvider<GitHub>()
provider.request(.zen) { result in
    switch result {
    case let .success(moyaResponse):
        let data = moyaResponse.data
        let statusCode = moyaResponse.statusCode
        // do something with the response data or statusCode
    case let .failure(error):
        // this means there was a network failure - either the request
        // wasn't sent (connectivity), or no response was received (server
        // timed out).  If the server responds with a 4xx or 5xx error, that
        // will be sent as a ".success"-ful response.
    }
}

That’s a basic example. Many API requests need parameters. Moya encodes these into the enum you use to access the endpoint, like this:

provider = MoyaProvider<GitHub>()
provider.request(.userProfile("ashfurrow")) { result in
    // do something with the result
}

No more typos in URLs. No more missing parameter values. No more messing with parameter encoding.

For more examples, see the documentation.

Reactive Extensions

Even cooler are the reactive extensions. Moya provides reactive extensions for ReactiveSwift, RxSwift, and Combine.

ReactiveSwift

ReactiveSwift extension provides both reactive.request(:callbackQueue:) and reactive.requestWithProgress(:callbackQueue:) methods that immediately return SignalProducers that you can start, bind, map, or whatever you want to do. To handle errors, for instance, we could do the following:

provider = MoyaProvider<GitHub>()
provider.reactive.request(.userProfile("ashfurrow")).start { event in
    switch event {
    case let .value(response):
        image = UIImage(data: response.data)
    case let .failed(error):
        print(error)
    default:
        break
    }
}

RxSwift

RxSwift extension also provide both rx.request(:callbackQueue:) and rx.requestWithProgress(:callbackQueue:) methods, but return type is different for both. In case of a normal rx.request(:callbackQueue), the return type is Single<Response> which emits either single element or an error. In case of a rx.requestWithProgress(:callbackQueue:), the return type is Observable<ProgressResponse>, since we may get multiple events from progress and one last event which is a response.

To handle errors, for instance, we could do the following:

provider = MoyaProvider<GitHub>()
provider.rx.request(.userProfile("ashfurrow")).subscribe { event in
    switch event {
    case let .success(response):
        image = UIImage(data: response.data)
    case let .error(error):
        print(error)
    }
}

In addition to the option of using signals instead of callback blocks, there are also a series of signal operators for RxSwift and ReactiveSwift that will attempt to map the data received from the network response into either an image, some JSON, or a string, with mapImage(), mapJSON(), and mapString(), respectively. If the mapping is unsuccessful, you’ll get an error on the signal. You also get handy methods for filtering out certain status codes. This means that you can place your code for handling API errors like 400’s in the same places as code for handling invalid responses.

Combine

Combine extension provides requestPublisher(:callbackQueue:) and requestWithProgressPublisher(:callbackQueue) returning AnyPublisher<Response, MoyaError> and AnyPublisher<ProgressResponse, MoyaError> respectively.

Here’s an example of requestPublisher usage:

provider = MoyaProvider<GitHub>()
let cancellable = provider.requestPublisher(.userProfile("ashfurrow"))
    .sink(receiveCompletion: { completion in
        guard case let .failure(error) = completion else { return }

        print(error)
    }, receiveValue: { response in
        image = UIImage(data: response.data)
    })

Community Projects

Moya has a great community around it and some people have created some very helpful extensions.

Contributing

Hey! Do you like Moya? Awesome! We could actually really use your help!

Open source isn’t just writing code. Moya could use your help with any of the following:

• Finding (and reporting!) bugs.
• New feature suggestions.
• Answering questions on issues.
• Documentation improvements.
• Reviewing pull requests.
• Helping to manage issue priorities.
• Fixing bugs/new features.

If any of that sounds cool to you, send a pull request! After your first contribution, we will add you as a member to the repo so you can merge pull requests and help steer the ship 🚢 You can read more details about that in our contributor guidelines.

Moya’s community has a tremendous positive energy, and the maintainers are committed to keeping things awesome. Like in the CocoaPods community, always assume positive intent. Even if a comment sounds mean-spirited, give the person the benefit of the doubt.

Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms.

Adding new source files

If you add or remove a source file from Moya, a corresponding change needs to be made to the Moya.xcodeproj project at the root of this repository. This project is used for Carthage. Don’t worry, you’ll get an automated warning when submitting a pull request if you forget.

Help us improve Moya documentation

Whether you’re a core member or a user trying it out for the first time, you can make a valuable contribution to Moya by improving the documentation. Help us by:

• Sending us feedback about something you thought was confusing or simply missing.
• Suggesting better wording or ways of explaining certain topics.
• Sending us a pull request via GitHub.
• Improving the Chinese documentation.

Moya on GitHub: https://github.com/Moya/Moya
Platform: iOS
⭐️: 14.8K