(Swift 3,4,5...) Egyptian eReceipt OAuth2 Client Credentials

See more Egypt eReceipt Examples

Get an OAuth2 access token for the Egyptian eReceipt REST API using client credentials (no interactivity with a web browser required).

For more information, see https://sdk.invoicing.eta.gov.eg/ereceiptapi/01-authenticate-pos/

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

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

    let http = CkoHttp()!
    var success: Bool

    // Note: Any provider of a REST API, such as the Egyptian government in this case, can make life 
    // much easier for developers by providing one or more of the following in the API documentation:
    // 
    // 1) A sample CURL statement for each API call.
    // 2) A Postman collection, or Swagger/OpenAPI specification file.
    // 3) A sample of a raw HTTP request and response for each API call.
    // 
    // The sample CURL statements or raw HTTP request/responses do not need to comprehensively show all 
    // possible options.  Providing a sample allows one to quickly make a successful API call.
    // It also allows for code generation directly from the CURL, Postman collection, or raw request/response,
    // and it tends to answer all questions about the format/structure of a request that, suprisingly,
    // remain ambiguous or not obvious in other forms of documentation.

    let req = CkoHttpRequest()!
    req.addParam("grant_type", value: "client_credentials")
    // Use your actual client ID and client secret...
    req.addParam("client_id", value: "d0394a9f-0607-40de-a978-2d3eb8375b04")
    req.addParam("client_secret", value: "6d62315e-d65a-4e41-9112-4195ea834edf")

    req.addHeader("posserial", value: "1234567899")
    req.addHeader("pososversion", value: "os")
    req.addHeader("posmodelframework", value: "1")
    req.addHeader("presharedkey", value: "03ac674216f3e1...")

    // When writing this example, the documentation at https://sdk.invoicing.eta.gov.eg/ereceiptapi/01-authenticate-pos/
    // shows us the HTTP verb and path (POST /connect/token), however,
    // we don't see the actual domain where the request is to be sent.
    // What are the endpoints???
    // It took some searching, but we found some endpoints here:  https://sdk.invoicing.eta.gov.eg/faq/
    // It's not immediately apparent which endpoint is to be used with a given API call.
    // Why not just include the endpoint in the documentation for each REST API call?
    // Endpoints are literally the #1 thing that needs to be known.
    // They can't just be buried in a FAQ.  They should be up-front and obvious.
    // 
    // So.. we're guessing the endpoint is likely "https://invoicing.eta.gov.eg/connect/token"
    var resp: CkoHttpResponse? = http.postUrlEncoded("https://invoicing.eta.gov.eg/connect/token", req: req)
    if http.lastMethodSuccess == false {
        print("\(http.lastErrorText!)")
        return
    }

    let sbResponseBody = CkoStringBuilder()!
    resp!.getBodySb(sbResponseBody)

    let jResp = CkoJsonObject()!
    jResp.loadSb(sbResponseBody)
    jResp.emitCompact = false

    print("Response Body:")
    print("\(jResp.emit()!)")

    var respStatusCode: Int = resp!.statusCode.intValue
    print("Response Status Code = \(respStatusCode)")
    if respStatusCode >= 400 {
        print("Response Header:")
        print("\(resp!.header!)")
        print("Failed.")
        resp = nil
        return
    }

    resp = nil

    // If successful, the OAuth2 access token JSON looks like this:

    // {
    //   "token_type": "Bearer",
    //   "access_token": "eyJraW......R2sbqrY",
    //   "expires_in": "3600",
    //   "scope": "..."
    // }

    var token_type: String? = jResp.string(of: "token_type")
    var access_token: String? = jResp.string(of: "access_token")
    var expires_in: String? = jResp.string(of: "expires_in")
    var scope: String? = jResp.string(of: "scope")

}