Integrating Systems Into a Swift App

Steps to Integrate Paytm via the SDK

1. Import the Library

A library can be imported via two processes:

a) Via pods

• Add pod 'Paytm-Payments' in the pod file.
• Run 'pod install' from the terminal.
• Open the xcworkspace.
• Go to "Link Binary With Libraries" in the "Build Phases" in the project settings, and add SystemConfiguration.framework.
• Check if PaytmSDK.framework is added in both “Link Binary With Libraries” and “Embedded Binaries.” If not, add it by clicking on the plus icon.

b) Directly add the library to the project

• Download the SDK from https://github.com/Paytm-Payments/Paytm_iOS_App_Kit/tree/master/Swift.
• Add Paytm.framework to the project.
• Go to "Link Binary With Libraries" in the "Build Phases" in the project settings, and add SystemConfiguration.framework.
• Check if PaytmSDK.framework is added in both “Link Binary With Libraries” and “Embedded Binaries.” If not, add it by clicking on the plus icon.

2. Add PaytmSDK to ViewController

import PaymentSDK

3. Generate Checksum

Checksumhash is a unique id used by Paytm to ensure that the transaction has not been tampered with. Checksumhash is generated on the server-side.

4. Start the Payment Process

A transaction can be made via the following processes:

1. First, choose the Paytm server based on the environment. For staging, create an instance of the  PGServerEnvironment and set the serverType to eServerTypeStaging. For production, create an instance of the PGServerEnvironment and set the serverType to eServerTypeProduction.
2. Now create the PGOrder instance with all the parameters.
3. Create the PGTransactionViewController instance by calling initTransactionForOrder and pass the instance of PGOrder as a parameter.

    private func setupPaytm() {

        serv = serv.createStagingEnvironment()
        let type :ServerType = .eServerTypeStaging
        let order = PGOrder(orderID: "", customerID: "", amount: "", eMail: "", mobile: "")

        order.params = ["MID":"rxazcv89315285234363",
                        "ORDER_ID":"order1",
                        "CUST_ID": "121",
                        "CHANNEL_ID":"WAP",
                        "INDUSTRY_TYPE_ID":"Retail",
                        "WEBSITE": "APP_STAGING",
                        "TXN_AMOUNT": "1024",
                        "CHECKSUMHASH":"oCDBVF+hvVb68JvzbKI40TOtcxlNjMdixi9FnRSh80Ub7XfjvgNr9NrfrOCPLmt65UhStCkrDnlYkclz1qE0uBMOrmuKLGlybuErulbLYSQ=",
                        "CALLBACK_URL" :"https://securegw-stage.paytm.in/theia/paytmCallback?ORDER_ID=order1"]

        self.txnController =  self.txnController.initTransaction(for: order) as?PGTransactionViewController
        self.txnController.title = "Paytm Payments"
        self.txnController.setLoggingEnabled(true)

        if(type != ServerType.eServerTypeNone) {
            self.txnController.serverType = type;
        } else {
            return
        }

        self.txnController.merchant = PGMerchantConfiguration.defaultConfiguration()
        self.txnController.delegate = self

        self.navigationController?.pushViewController(self.txnController
            , animated: true)
    }

5. Implement the 'PGTransactionDelegate' Protocol

Implement the 'PGTransactionDelegate'  protocol in the view-controller from where payments are made:

//MARK : Delegate Methods

extension ScheduleOnOderVC : PGTransactionDelegate {

    //this function triggers when transaction gets finished
    func didFinishedResponse(_ controller: PGTransactionViewController, response responseString: String) {

        let msg : String = responseString
        var titlemsg : String = ""
        if let data = responseString.data(using: String.Encoding.utf8) {
            do {
                if let jsonresponse = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? [String:Any] , jsonresponse.count > 0{
                    titlemsg = jsonresponse["STATUS"] as? String ?? ""
                }
            } catch {
                print("Something went wrong")
            }
        }

        let actionSheetController: UIAlertController = UIAlertController(title: titlemsg , message: msg, preferredStyle: .alert)
        let cancelAction : UIAlertAction = UIAlertAction(title: "OK", style: .cancel) {
            action -> Void in
            controller.navigationController?.popViewController(animated: true)
        }
        actionSheetController.addAction(cancelAction)
        self.present(actionSheetController, animated: true, completion: nil)
    }
    //this function triggers when transaction gets cancelled
    func didCancelTrasaction(_ controller : PGTransactionViewController) {
        controller.navigationController?.popViewController(animated: true)
    }
    //Called when a required parameter is missing.
    func errorMisssingParameter(_ controller : PGTransactionViewController, error : NSError?) {
        controller.navigationController?.popViewController(animated: true)
    }
}

6. Verify Checksum

Checksumhash needs to be verified so that we know the response has not been tampered with. Again, verification is done on the server-side.