Making HTTP requests

Making http requests is one of the first things people try.

You first need to build NSURLRequest object that represents the work that needs to be done.

Request determines is it a GET request, or a POST request, what is the request body, query parameters ...

This is how you can create a simple GET request

let req = URLRequest(url: NSURL(string: "http://en.wikipedia.org/w/api.php?action=parse&page=Pizza&format=json"))

If you want to just execute that request outside of composition with other observables, this is what needs to be done.

let responseJSON = URLSession.shared.rx.json(request: req)

// no requests will be performed up to this point
// `responseJSON` is just a description how to fetch the response


let cancelRequest = responseJSON
    // this will fire the request
    .subscribe(onNext: { json in
        print(json)
    })

Thread.sleep(forTimeInterval: 3.0)

// if you want to cancel request after 3 seconds have passed just call
cancelRequest.dispose()

URLSession extensions don't return result on MainScheduler by default.

In case you want a more low level access to response, you can use:

URLSession.shared.rx.response(myNSURLRequest)
    .debug("my request") // this will print out information to console
    .flatMap { (data: NSData, response: URLResponse) -> Observable<String> in
        if let response = response as? HTTPURLResponse {
            if 200 ..< 300 ~= response.statusCode {
                return just(transform(data))
            }
            else {
                return Observable.error(yourNSError)
            }
        }
        else {
            rxFatalError("response = nil")
            return Observable.error(yourNSError)
        }
    }
    .subscribe { event in
        print(event) // if error happened, this will also print out error to console
    }

Logging HTTP traffic

In debug mode RxCocoa will log all HTTP request to console by default. In case you want to change that behavior, please set Logging.URLRequests filter.

// read your own configuration
public struct Logging {
    public typealias LogURLRequest = (URLRequest) -> Bool

    public static var URLRequests: LogURLRequest =  { _ in
    #if DEBUG
        return true
    #else
        return false
    #endif
    }
}