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Moya/docs/ReactiveSwift.md

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# ReactiveSwift
Moya provides an optional `ReactiveSwift` implementation of
`MoyaProvider` that does a few interesting things. Instead of
calling the `request()` method and providing a callback closure
to be executed when the request completes, we use `SignalProducer`s.
To use reactive extensions you don't need any additional setup.
Just use your `MoyaProvider` instance.
```swift
let provider = MoyaProvider<GitHub>()
```
After that simple setup, you're off to the races:
```swift
provider.reactive.request(.zen).start { event in
switch event {
case let .value(response):
// do something with the data
case let .failed(error):
// handle the error
default:
break
}
}
```
You can also use `requestWithProgress` to track progress of
your request:
```swift
provider.reactive.requestWithProgress(.zen).start { event in
switch event {
case .value(let progressResponse):
if let response = progressResponse.response {
// do something with response
} else {
print("Progress: \(progressResponse.progress)")
}
case .failed(let error):
// handle the error
default:
break
}
}
```
It's important to remember that network request is not started
until the signal is subscribed to. If the subscription to the signal
is disposed of before the request completes, the request is canceled.
If the request completes normally, two things happen:
1. The signal sends a value, a `Moya.Response` instance.
2. The signal completes.
If the request produces an error (typically a URLSession error),
then it sends an error, instead. The error's `code` is the failing
request's status code, if any, and the response data, if any.
The `Moya.Response` class contains a `statusCode`, some `data`,
and a(n optional) `HTTPURLResponse`. You can use these values however
you like in `startWithNext` or `map` calls.
To make things even awesomer, Moya provides some extensions to
`SignalProducer` that make dealing with `Moya.Responses`
really easy.
- `filter(statusCodes:)` takes a range of status codes. If the
response's status code is not within that range, an error is
produced.
- `filter(statusCode:)` looks for a specific status code, and errors
if it finds anything else.
- `filterSuccessfulStatusCodes()` filters status codes that
are in the 200-range.
- `filterSuccessfulStatusAndRedirectCodes()` filters status codes
that are in the 200-300 range.
- `mapImage()` tries to map the response data to a `UIImage` instance
and errors if unsuccessful.
- `mapJSON()` tries to map the response data to a JSON object and
errors if unsuccessful.
- `mapString()` tries to map the response data to a string and
errors if unsuccessful.
- `mapString(atKeyPath:)` tries to map a response data key path to a string and
errors if unsuccessful.
In the error cases, the error's `domain` is `MoyaErrorDomain`. The code
is one of `MoyaErrorCode`'s `rawValue`s, where appropriate. Wherever
possible, underlying errors are provided and the original response
data is included in the `NSError`'s `userInfo` dictionary using the
"data" key.