For #695.
The biggest change is that this code at the beginning of `HTTPClient.handle` is now gone:
```swift
var statusCode: HTTPStatusCode = .networkConnectTimeoutError
var jsonObject: [String: Any]?
var httpResponse: HTTPResponse? = HTTPResponse(statusCode: statusCode, jsonObject: jsonObject)
var receivedJSONError: Error?
```
It was hard to trace which paths modified these default values. The new implementation has a mostly linear path (part of it abstracted in smaller methods now) and doesn’t have mutable values.
This is the new `handle` implementation:
```swift
func handle(urlResponse: URLResponse?,
request: Request,
urlRequest: URLRequest,
data: Data?,
error networkError: Error?) {
let (response, shouldRetry) = self.parse(
urlResponse: urlResponse,
request: request,
urlRequest: urlRequest,
data: data,
error: networkError
)
if shouldRetry {
Logger.debug(Strings.network.retrying_request(httpMethod: request.method.httpMethod,
path: request.path))
self.state.modify {
$0.queuedRequests.insert(request.retriedRequest(), at: 0)
}
} else {
request.completionHandler?(response)
}
self.beginNextRequest()
}
```
## All Changes:
- `HTTPClient.perform` no longer has a bunch of mutable variables with forking paths that make it hard to follow. Most of the response handling is now in a new `parse` method. This will simplify the task of continuing to refactor response deserialization.
- `HTTPClient`’s completion abstracts response into `HTTPResponse`
- `UserInfoAttributeParser` is now an `enum`
- `ETagManager` no longer takes an `Error`. The only thing it did with it is to return the default response.
- `HTTPResponse.jsonObject` is no longer `Optional`
- Moved `defaultJsonEncoder` / `defaultJsonDecoder` to `JSONDecoder+Extensions`. They used by `HTTPClient` and others soon.
NachoSoto