To check the status of a transaction, you need its order id and type, whether it’s a Purchase or a Refund. The method will retrieve the transaction’s status and reference:

MobilePaymentSDK.getOrderStatusFor(orderId,
                                   transactionType: type,
                                   completed: { (status, reference) in
                                    self.showAlertWithText("Order \(orderId). " +
                                                           "Status - \(status) | " + 
                                                           "Reference - \(reference)")
},
                                   failed: { (error) in
                                    self.showAlertWithText("Error while getting order status: " +
                                                           "\(error.message)")
})

[MobilePaymentSDK getOrderStatusFor:_orderId
                    transactionType:_transactionType
                          completed:^(NSInteger status, NSString * _Nonnull paymentRef) {
                              [self showAlertWithText:[NSString stringWithFormat:
                                                      @"Order %@. Status - %ld | Reference - %@",
                                                      orderId, status, paymentRef]];
                           } failed:^(MobilePaymentSDKError * _Nonnull error) {
        			  [self showAlertWithText:[NSString stringWithFormat:
                                                      @"Error while getting order status: %ld", status]];
                           }];