(Swift 3,4,5...) Get Access Token using a Pre-Created JSON Web Token

Demonstrates how to get an access token using a pre-created JSON Web Token (JWT).

For more information, see https://developer.abnamro.com/get-started#headingFive

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

func chilkatTest() {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // We're going to duplicate this CURL statement:
    // curl -X POST https://api-sandbox.abnamro.com/v1/oauth/token \
    // -H "Content-Type: application/x-www-form-urlencoded" \
    // -H "API-Key: xxxxxx" \
    // -d 'client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer&grant_type=client_credentials&client_assertion=eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ4eHh4eHgiLCJleHAiOiIxNDk5OTQ3NjY4IiwiaXNzIjoibWUiLCJhdWQiOiJodHRwczovL2F1dGgtc2FuZGJveC5hYm5hbXJvLmNvbS9vYXV0aC90b2tlbiJ9.jGwHKG_YjgKpR8NPpaLu6nJ97obeP2vcxg6fOWBKdJ0&scope=tikkie'

    // Load our pre-creaed private key PEM file.
    // Note: Please share your public key along with your app name and developer email id at api.support@nl.abnamro.com. 
    // Token generation will not work unless public key is associated with your app.
    let privkey = CkoPrivateKey()!

    var success: Bool = privkey.loadPemFile("qa_data/pem/abnAmroPrivateKey.pem")
    if success == false {
        print("\(privkey.lastErrorText!)")
        return
    }

    // Create the JWT.
    let jwt = CkoJwt()!

    // Create the header:
    // {
    //     "typ": "JWT",
    //     "alg": "RS256"
    // }
    let jsonHeader = CkoJsonObject()!
    jsonHeader.update("typ", value: "JWT")
    jsonHeader.update("alg", value: "RS256")

    // Create the payload:
    // {
    //     "nbf": 1499947668,
    //     "exp": 1499948668,
    //     "iss": "me",
    //     "sub": "anApiKey",
    //     "aud": "https://auth-sandbox.abnamro.com/oauth/token"
    // }
    let jsonPayload = CkoJsonObject()!

    var curDateTime: Int = jwt.genNumericDate(0).intValue

    // Set the "not process before" timestamp to now.
    success = jsonPayload.addInt(at: -1, name: "nbf", value: curDateTime)

    // Set the timestamp defining an expiration time (end time) for the token
    // to be now + 1 hour (3600 seconds)
    success = jsonPayload.addInt(at: -1, name: "exp", value: curDateTime + 3600)

    jsonPayload.update("iss", value: "me")
    jsonPayload.update("sub", value: "anApiKey")
    jsonPayload.update("aud", value: "https://auth-sandbox.abnamro.com/oauth/token")

    // Produce the smallest possible JWT:
    jwt.autoCompact = true

    var jwtStr: String? = jwt.createJwtPk(jsonHeader.emit(), payload: jsonPayload.emit(), key: privkey)
    if jwt.lastMethodSuccess != true {
        print("\(jwt.lastErrorText!)")
        return
    }

    let http = CkoHttp()!

    let req = CkoHttpRequest()!
    req.addParam("client_assertion_type", value: "urn:ietf:params:oauth:client-assertion-type:jwt-bearer")
    req.addParam("grant_type", value: "client_credentials")
    req.addParam("client_assertion", value: jwtStr)
    req.addParam("scope", value: "tikkie")

    var resp: CkoHttpResponse? = http.postUrlEncoded("https://api-sandbox.abnamro.com/v1/oauth/token", req: req)
    if http.lastMethodSuccess == false {
        print("\(http.lastErrorText!)")
        return
    }

    if resp!.statusCode.intValue != 200 {
        print("\(resp!.bodyStr!)")
        resp = nil
        return
    }

    // Get the JSON result:
    // {
    //     "access_token": "{your access token}",
    //     "expires_in": "{duration of validity in seconds}",
    //     "scope": "{scope(s) for which the access token is valid}",
    //     "token_type": "{it is always Bearer}"
    // }
    let json = CkoJsonObject()!
    json.load(resp!.bodyStr)
    print("access_token: \(json.string(of: "access_token")!)")
    print("token_type: \(json.string(of: "token_type")!)")
    print("expires_in: \(json.string(of: "expires_in")!)")
    print("scope: \(json.string(of: "scope")!)")

    resp = nil

}