Moya

A Chinese version of this document can be found here.

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 new auction app. We consider it ready for production use.

Installation

Moya version vs Swift version.

Below is a table that shows which version of Moya you should use for your Swift version.

Swift	Moya	RxMoya	ReactiveMoya
4.X	>= 9.0	>= 10.0	>= 9.0
3.X	8.0.0 - 8.0.5	8.0.0 - 8.0.5	8.0.0 - 8.0.5
2.3	7.0.2 - 7.0.4	7.0.2 - 7.0.4	7.0.2 - 7.0.4
2.2	<= 7.0.1	<= 7.0.1	<= 7.0.1

Upgrading to a new major version of Moya? Check out our migration guides.

Swift Package Manager

To integrate using Apple's Swift package manager, add the following as a dependency to your Package.swift:

.package(url: "https://github.com/Moya/Moya.git", .upToNextMajor(from: "12.0.0"))

and then specify "Moya" as a dependency of the Target in which you wish to use Moya. If you want to use reactive extensions, add also "ReactiveMoya" or "RxMoya" as your Target dependency respectively. Here's an example PackageDescription:

// swift-tools-version:4.0
import PackageDescription

let package = Package(
    name: "MyPackage",
    products: [
        .library(
            name: "MyPackage",
            targets: ["MyPackage"]),
    ],
    dependencies: [
        .package(url: "https://github.com/Moya/Moya.git", .upToNextMajor(from: "12.0.0"))
    ],
    targets: [
        .target(
            name: "MyPackage",
            dependencies: ["ReactiveMoya"])
    ]
)

Note that as of Moya 10, SPM only works with Swift 4 toolchain and greater.

CocoaPods

For Moya, use the following entry in your Podfile:

pod 'Moya', '~> 12.0'

# or 

pod 'Moya/RxSwift', '~> 12.0'

# or

pod 'Moya/ReactiveSwift', '~> 12.0'

Then run pod install.

In any file you'd like to use Moya in, don't forget to import the framework with import Moya.

Carthage

Carthage users can point to this repository and use whichever generated framework they'd like, Moya, RxMoya, or ReactiveMoya.

Make the following entry in your Cartfile:

github "Moya/Moya"

Then run carthage update.

If this is your first time using Carthage in the project, you'll need to go through some additional steps as explained over at Carthage.

NOTE: At this time, Carthage does not provide a way to build only specific repository submodules. All submodules and their dependencies will be built with the above command. However, you don't need to copy frameworks you aren't using into your project. For instance, if you aren't using ReactiveSwift, feel free to delete that framework along with ReactiveMoya from the Carthage Build directory after carthage update completes. Or if you are using ReactiveSwift but not RxSwift, then RxMoya, RxTest, RxCocoa, etc. can safely be deleted.

Manually

Open up Terminal, cd into your top-level project directory, and run the following command if your project is not initialized as a git repository:

$ git init

Add Alamofire, Result & Moya as a git submodule by running the following commands:

$ git submodule add https://github.com/Alamofire/Alamofire.git
$ git submodule add https://github.com/antitypical/Result.git
$ git submodule add https://github.com/Moya/Moya.git

Open the new Alamofire folder, and drag the Alamofire.xcodeproj into the Project Navigator of your application's Xcode project. Do the same with the Result.xcodeproj in the Result folder and Moya.xcodeproj in the Moya folder.

They should appear nested underneath your application's blue project icon. Whether it is above or below all the other Xcode groups does not matter.

Verify that the deployment targets of the xcodeprojs match that of your application target in the Project Navigator.
Next, select your application project in the Project Navigator (blue project icon) to navigate to the target configuration window and select the application target under the "Targets" heading in the sidebar.
In the tab bar at the top of that window, open the "General" panel.
Click on the + button under the "Embedded Binaries" section.
You will see two different Alamofire.xcodeproj folders each with two different versions of the Alamofire.framework nested inside a Products folder.

It does not matter which Products folder you choose from, but it does matter whether you choose the top or bottom Alamofire.framework.

Select the top Alamofire.framework for iOS and the bottom one for macOS.

You can verify which one you selected by inspecting the build log for your project. The build target for Alamofire will be listed as either Alamofire iOS, Alamofire macOS, Alamofire tvOS or Alamofire watchOS.

Click on the + button under "Embedded Binaries" again and add the build target you need for Result.
Click on the + button again and add the correct build target for Moya.
And that's it!

The three frameworks are automagically added as a target dependency, linked framework and embedded framework in a copy files build phase which is all you need to build on the simulator and a device.

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 and RxSwift.

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.

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

License

Moya is released under an MIT license. See License.md for more information.

dpoggi/Moya