Welcome to a new week. This week, we will be looking
at how to use App Inventor to send shortcodes.
Shortcodes are numbers meant for services that are
created in collaboration with a telecoms provider. The aim of which is to carry
out a particular functionality in the telecoms system.
The service I will be using as an example is the
Bank 737 shortcode service from GTB. Now I am not a staff of GTB only a
customer who got dissatisfied with the inconvenience of having to type *737*
every time I wanted to perform an operation.
During the course of developing this application, I
learned how to use shortcodes in App Inventor. Special thanks go to @puravidaapps for
insight on how to do this.
The system architecture for this service is shown
below:
Bank1337 is simply a frontend to the Bank 737
shortcodes. It starts the process of contacting the shortcode service. Once it
does that, the GTB USSD API takes over and continues the interaction with the
user.
The shortcodes that power this service are shown
below:
Getting Started
Using the NICE method, our first step would be to
name our application. In my case, I named my application Bank1337. 1337
represents Leet. We don’t use the name Bank 737 because we don’t have the copyright
and we wouldn’t want GTB to come after us J.
Choose a name for your project and let’s start
creating our application. Last week, we covered how to create a multi-screen
applications so I won’t go over it here again.
For the shortcodes, there are 9 things we can do.
They are listed below:
- Buy Airtime (Self)
- Buy Airtime (Third Party)
- Transfer to GTBank
- Transfer to Other Banks
- Pay Bills (Startimes)
- Internet Banking Details
- Generate Token Code
- Account Opening
- Balance Check/Enquiry
The code for the Bank1337 application has been
placed in the App Inventor Gallery. For the purposes of this tutorial, I shall
only explain how to create the code for the first operation. Please search the App Inventor Gallery for the source code.
User
Interface
The operations 1 to 5 will have their own screens
while the remaining can be done from the first screen.
Our first screen looks as shown below:
Once the user presses any of the first five operations, it should go to a new screen. The remaining can be done using the first screen. In total, this application has 6 screens.
For the first operation, we use a simple user
interface to retrieve the amount of airtime the user wants to buy. This is
shown below:
For our textbox component, we want to ensure that the user enters a number and that the number entered is less than N1000.
The NumbersOnly property of our textboxes are set to
ensure that only numbers are entered in the textboxes. This is done for all the
textboxes used throughout this application.
Since the code is available online, I will show you
the code that moves from one screen to the other. This is shown below:
Once we click on the first button, the program redirects to Screen2. On Screen2 we perform our operation.
The code for Screen2 is shown below:
The only component we have not seen before is the
PhoneCall component. This is found in the Social drawer of the Palette.
The PhoneCall component allows you to make phone
calls using App Inventor. The PhoneNumber of the PhoneCall component must be
set to the shortcode value along with the value in the textbox.
Note the %23 which is the Unicode value of #. App
Inventor does not allow you to use # so we trick the component into making a
call with its Unicode value.
At the end of the day, every character is converted
to Unicode so using this method, we ensure that the # is attached at the end of
our shortcode. So what is going to be set as the phone number of the PhoneCall
component is going to be in format *737*AMOUNT%23.
Conclusion
This week, we created a simple application to work
with the shortcode service from GTB. While the original shortcode service is
simple, the Bank1337 application adds accuracy and convenience to the mix.
The source code for the Bank1337 application is
available in the App Inventor Gallery and you can also download the final
application from the Google Play Store.
The gift of being able to program is the fact that
you can create. You don’t have to accept the world as it is you can create
solutions to meet your needs. Once you learn to program, you can bend computers
to your will and make them do whatever you want.
As a Nigerian I testify that the world is gradually moving to the stage where smartphones and hence computers surround us everyday. So learning how to program is starting to look like a super power.
