#import <PaySMSSDK/PaySMSSDK.h>

    NSString* moCode = @"YOUR_APP_MO_CODE";
    NSString* accountName = @"USER_ACCOUNT_NAME_OR_ID";
    paySMSClient = [[PaySMSClient alloc] initWithMOCode:moCode
                                            accountName:accountName];
    paySMSClient.dataSource = self;

- (NSString * _Nullable)partnerCodeForAmount:(PaySMSAmount * _Nonnull)amount {
    // You can custom telecom service code here
    // Ex: For Mobifone, there are VTC and BX codes. The default value is VTC,
    // but you can choose the BX code by "return" BX value here.
    if (amount.provider == kPaySMSProviderMobifone) {
        return @"BX";
    }
    // It is also you can choose BX as partner Code for Vinaphone
    else if (amount.provider == kPaySMSProviderVinaphone) {
        // For BX, there is no amount with value == 100K, so,
        // if the amount == 100K, and you choose "BX", it will raise the Assertion
        return @"BX";
    } else if (amount.provider == kPaySMSProviderViettel) {
        // For BX, there is no amount with value == 100K, so,
        // if the amount == 100K, and you choose "BX", it will raise the Assertion
        return @"QK";
    }

    // When this function return null or the listener is nil/NULL,
    // it will using VTC as default partner code
    return nil;
}

    // the paySMSClient you already inited above 
    PaySMSController* paySMSController = [[PaySMSController alloc]  initWithSMSClient:paySMSClient];
    paySMSController.delegate = self;
    // implement PaySMSControllerDelegate for custom the telecom and par value
    [self presentViewController:paySMSController
                       animated:YES
                     completion:nil];                     

/**
 *  This function for developer can set the list of telecom, that the game/app supported
 *  This function is optional, and if the function return null or an empty array list,
 *  the SDK will show all Providers
 *
 *  @param viewController The PaySMSController
 */
- (NSArray*)supportedProviders:(PaySMSController * _Nonnull)viewController {
    //this is an example when you want user choose Mobilfone or Vinaphone only
      NSArray* supportedProviders = @[@(kPaySMSProviderMobifone),
                                    @(kPaySMSProviderVinaphone)];
      return supportedProviders;
}

/**
 *  This function for developer can set the list of fair values for providers
 *  This function is optional, and if the function return null or an empty array list,
 *  the SDK still show all available fair values
 *
 *  @param viewController The PDVoucherUseCardViewController its delegate of fail
 *  @param result         The selected (and possibly newly created) tokenized payment information.
 */
- (NSArray*)availableFairValuesForProvider:(PaySMSProvider)provider
                              inController:(PaySMSController * _Nonnull)viewController {

    // This is the way you want user to pick some par values only
    // An example with Viettel
    if (provider == kPaySMSProviderViettel) {
        return @[@(kPaySMSParValue1K),
                 @(kPaySMSParValue5K),
                 @(kPaySMSParValue10K)];
    }    
}

/**
 *  Informs the delegate when the user has decided to cancel out of the Pay by SMS form.
 *
 *  @param viewController The PaySMSController view controller informing its delegate of failure or cancelation.
 */
- (void)userDidCancel:(PaySMSController * _Nonnull)viewController {
    // By simple way, you just need to dissmis the PaySMSController
    [viewController dismissViewControllerAnimated:YES
                                       completion:nil];
}

/**
 *  Informs the delegate when the sms did send
 *
 *  @param viewController The PaySMSController view controller informing its delegate of failure or cancelation.
 */
- (void)smsDidSend:(PaySMSController * _Nonnull)viewController {
    // Thanks for user and check your server side to be sure your got money from user
    [self.alert cancelAlertWithTitle:nil
                             message:NSLocalizedString(@"The SMS did sent", @"The SMS did sent")
                         cancelTitle:NSLocalizedString(@"OK", @"OK")
                       cancelHandler:^{}];
}

/**
 *  Informs the delegate when the sms failed
 *
 *  @param viewController The PaySMSController view controller informing its delegate of failure.
 */
- (void)smsFailed:(PaySMSController * _Nonnull)viewController {
    [self.alert cancelAlertWithTitle:nil
                             message:NSLocalizedString(@"Can not send SMS", @"Can not send SMS")
                         cancelTitle:NSLocalizedString(@"OK", @"OK")
                       cancelHandler:^{}];
}

    // Init an amount to charge by PaySMS 
    PaySMSAmount* amount = [[PaySMSAmount alloc] init];
    // Set your telecom: Mobilfone/Vinaphone or Viettel. It should be the user's telecom.
    amount.provider = kPaySMSProviderMobifone;
    // The par value to charge by PaySMS: 1K, 2K, 3K, 4K, 5K, 10K, 15K, 20K, 30K, 40K, 50K, 100K
    amount.parValue = kPaySMSParValue1K;


    // Generate the SMS Syntax 
    NSString* smsSyntax = [paySMSClient smsSyntax:amount];

    // In case the par value is not supported by telecom, the smsSyntax returned will be nil
    if (smsSyntax) {
        // It is an example for you can use 'smsSyntax', Alert to user 
        NSString * message = [NSString stringWithFormat:NSLocalizedString(@"The syntax is: %@. Do you want to send to the provider?", @"The syntax is: \"%@\". Do you want to send to the provider?"),smsSyntax];
        [self.alert alertWithTitle:nil
                           message:message
                            titles:@[NSLocalizedString(@"Yes", @"Yes"),
                                     NSLocalizedString(@"Cancel", @"Cancel")]
                          handlers:@[^{
            // And send SMS by using MFMessageComposeViewController
            if ([MFMessageComposeViewController canSendText]) {
                MFMessageComposeViewController *messageController = [[MFMessageComposeViewController alloc] init];
                messageController.messageComposeDelegate = self;
                [messageController setRecipients:@[@"9029"]];
                [messageController setBody:smsSyntax];

                [self presentViewController:messageController
                                   animated:YES
                                 completion:nil];
            }
        }, ^ {

        }]];
    }