How to add parameter to Almofire request

Question

Disclaimer: I'm new to iOS programming, so this question is probably as simple as it looks. It's not a trick question!

I've a Swift project that uses Almofire to send HTTP requests. I want to add a parameter to the query string for every single request made.

So, I want to add mykey=myval to every request.

• EG: http://example.com/index -> http://example.com/index?mykey=myval
• EG: http://example.com/index?key=val -> http://example.com/index?key=val&mykey=myval

I have found that all requests seem to go through

public func request(URLRequest: URLRequestConvertible) -> Request {
    return Manager.sharedInstance.request(URLRequest.URLRequest)
}

in a file named Almofire.swift

and also through

public func request(URLRequest: URLRequestConvertible) -> Request {
    var dataTask: NSURLSessionDataTask?
    dispatch_sync(queue) {
        dataTask = self.session.dataTaskWithRequest(URLRequest.URLRequest)
    }

    let request = Request(session: session, task: dataTask!)
    delegate[request.delegate.task] = request.delegate

    if startRequestsImmediately {
        request.resume()
    }

    return request
}

in a file named Manager.swift, so I'm presuming I need to add a bit of code here. Due to my lack of Swift knowledge I've spend hours experimenting but no joy - only exceptions.

Does anyone know how I can add a parameter to all requests?

Answer 1

You don't need to change anything in Alamofire's code. Instead you can use the URLRequestConvertible protocol to encapsulate your URLs and parameter in an enum:

enum Router: URLRequestConvertible {
    static let baseURLString = "https://example.com" // define your base URL here
    static var defaultParams = ["myKey": "myValue"] // set the default params here

    // define a case for every request you need
    case Index
    case Endpoint1(param: String)
    case Endpoint2(param1: String, param2: String)

    var URLRequest: NSMutableURLRequest {
        let result: (path: String, parameters: [String: AnyObject]) = {
            // set the path and params for each request
            switch self {
            case .Index:
                return ("/index", Router.defaultParams)
            case .Endpoint1(let param):
                var params = Router.defaultParams
                params.updateValue(param, forKey: "key")
                return ("/endpoint", params)
            case .Endpoint2(let param1, let param2):
                var params = Router.defaultParams
                params.updateValue(param1, forKey: "key1")
                params.updateValue(param2, forKey: "key2")
                return ("/endpoint2", params)
            }
        }()

        // create the URL and the request
        let URL = NSURL(string: Router.baseURLString)!
        let URLRequest = NSURLRequest(URL: URL.URLByAppendingPathComponent(result.path))
        let encoding = Alamofire.ParameterEncoding.URL

        return encoding.encode(URLRequest, parameters: result.parameters).0
    }
}

Then you can call your requests in the following matter:

// sends a request to 'https://example.com/index?myKey=myValue'
Alamofire.request(Router.Index).response { (request, urlResponse, data, error) -> Void in
    // handle response
}

// sends a request to 'https://example.com/endpoint?key=value&myKey=myValue'
Alamofire.request(Router.Endpoint1(param: "value")).response { (request, urlResponse, data, error) -> Void in
    // handle response
}

// sends a request to 'https://example.com/endpoint2?key1=value1&key2=value2&myKey=myValue'
Alamofire.request(Router.Endpoint2(param1: "value1", param2: "value2")).response { (request, urlResponse, data, error) -> Void in
    // handle response
}