Tag Archives: software

Free – download MIT App Inventor “Cheat Sheet”

I have created a “cheat sheet” that captures all of the App Inventor components, blocks, events, properties and procedure calls. The “cheat sheet” is 9 page of details, in a large (almost 5 MB) PDF file that contains high resolution images suitable for high res printing. For those learning App Inventor, the cheat sheet may help you quickly find various components within the interface.

Download here: App Inventor Cheat Sheet (PDF)

Feel free to share with others.

I have some ideas for additional cheat sheets but would like to hear what you might like to have in a “cheat sheet” summary format. Post comments here or on our Facebook group page. Thank you!

E-Books and Printed Books

If you find these tutorials helpful (I hope you do!) please take a look at my books on App Inventor. To learn more about the books and where to get them (they are inexpensive) please see my App Inventor Books page.

  • App Inventor 2 Introduction (Volume 1 e-book)
    Step-by-step guide to easy Android programming
  • App Inventor 2 Advanced Concepts (Volume 2 e-book)
    Step-by-step guide to Advanced features including TinyDB
  • App Inventor 2 Databases and Files (Volume 3 e-book)
    Step-by-step TinyDB, TinyWebDB, Fusion Tables and Files
  • App Inventor 2 Graphics, Animation and Charts (Volume 4 e-book and printed book)
    Step-by-step guide to graphics, animation and charts

Thank you for visiting! — Ed

How to Place Your App Inventor Apps in the Google Play Store

An all new tutorial on this subject is available here as of May 2016! There is still some great information below – read both!

Apps you create in App Inventor may be added to the Google Play Store.

The process is not difficult but there are many steps to the process and you will need to create some graphic images to illustrate and promote your app in the store.

Summary of the Steps

  • Set your app’s VersionCode and VersionName.
  • Apply for a Google Developer account (one time fee of US $25 after which you can upload an unlimited number of apps, forever).
  • Create at least two and up to 8 screenshots of your app for display in the store’s app listing.
  • Create a “feature graphic” and a high resolution icon for use in the store listing.
  • Use the App Inventor provided keystore file, or use a keystore file you have created elsewhere or previously.
  • Build and export your app as a .apk file to your computer.
  • Create a title for your app in the store
  • Write a description for your app to appear in the store
  • Decide on free versus paid (paid requires a “merchant account” to be set up).
  • Upload your apk file, keystore file, image files and title and description, and provide some additional information (such as product category, pricing, and target audience).

Continue reading How to Place Your App Inventor Apps in the Google Play Store

App Inventor introduces copy and paste of code blocks!

App Inventor has introduced “copy and paste” of code blocks. Now you can copy blocks of code within a current screen, or from one screen to another screen, or even between projects. This is great news!

Look for the “backpack” icon at upper right of the blocks Viewer screen:

AI_Copy1

Select a block or blocks with the mouse pointer, and then click and drag the selected blocks into the backpack. A copy of the blocks are placed into the backpack and your original blocks also remain in the editing window.

Click on the backpack icon and it displays the code blocks currently stored in the backpack:

AI_Copy2

Click on the code block in the backpack (at right) and drag it into the Blocks Viewer. That is all you need to do to copy blocks.

Use this feature to copy blocks within your current screen, or to copy blocks from one screen to another screen, or to copy blocks from one app to another app.

You can put several blocks into the backpack, and then select only the ones you wish to copy over to another blocks Viewer.

How do you empty the backpack? It seems the only way to empty the backpack of saved items is to close the editing windows, go back to the MIT App Inventor home page (http://appinventor.mit.edu/) and select the Create apps! button to re-enter the designer and blocks editor.

Regardless, this is a GREAT NEW FEATURE! Thanks MIT App Inventor team!

Implementing an “Array” in App Inventor

What is an “Array”?

An array is a variable data type that stores a collection of values referenced by an index number.

For example, suppose we wished to store the names of the 12 months of the year: January, February, March, … , November, December so we can convert a month number to a text name. Month 1 converts to “January”, Month 2 converts to “February” and Month 12 converts to “December”.

An easy way to do this conversion is to set up an array that, in concept, looks something like this:

Month[1] = “January”
Month[2] = “February”
Month[3] = “March”
Month[4] = “April”
Month[5] = “May”
Month[6] = “June”
Month[7] = “July”
Month[8] = “August”
Month[9] = “September”
Month[10] = “October”
Month[11] = “November”
Month[12] = “December”

Month is the name of this variable – but unlike other variables, this one stores 12 separate values. Each value is referenced by using an index – if the index value is 2, then Month[index] refers to “February”.

If we have a date, such as (US-style) – 2/14/15, meaning February 15, 2015, we can convert the month number of 2, into the text month name by referencing Month[2].

If you have studied algebra math or beyond, you have encountered array variables such as X1, X2, X3, … Xn where the value Xi is read as “X subscript i”. This is the same concept as an array of values. If you have not studied algebra, this notation may be new to you. 

Most programming languages support an array variable type but App Inventor does not support arrays. Yet arrays are a convenient way of storing and working with some types of data. To support an array-like variable in App Inventor, we can use a list and map the array subscript to an index position in the list.  By hiding this within a couple of procedures, we can simulate the array variable type.

Sample User Interface

I created a simple app to demonstrate the use and implementation of the array. You can download this app from the MIT App Inventor Gallery here.

Continue reading Implementing an “Array” in App Inventor

How to use the “2 Button” Notifier dialog box

A reader asked, “When using the 2 button Notifier dialog, how do we know which button was pressed?

The 2 button Notifier dialog alert box displays 3 buttons(!) – the first two have values you specify, such as “Ok” and “Done”, as shown here, and the third is an optional generic “Cancel” button:

Screenshot_2015-09-11-15-07-15

The Notifier component block is a procedure call that has no return value – so how can you determine which button was selected?

The answer is that the selected button is returned to a separate event handler.

Continue reading How to use the “2 Button” Notifier dialog box

Tip: Using component colors to find components in the Blocks Editor

Finding a specific programming block with in the AI2 Blocks editor can be hard for new AI programmers.

You found a great code example online and want to recreate it by entering the blocks in to your program – but you cannot find that red block in the middle of the code sample? Where is it? !!!

You start poking around the drop down lists, scanning up and down the pop up menus, missing it the first time(!) and then going through all the blocks again until you finally locate that darned block! Frustrating!

Continue reading Tip: Using component colors to find components in the Blocks Editor

App Inventor 2: Databases and Files – available shortly

Volume 3 – focusing on TinyDB, TinyWebDB, Fusion Tables and text files – is now Available.

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App Inventor 2: Databases and Files is a step-by-step guide to writing apps that use TinyDB, TinyWebDB, Fusion Tables and data files for information storage and retrieval. Includes detailed explanations, examples, and a link to download sample code. This is the first tutorial to cover all of these App Inventor database and file features.

If your apps need to work with data or files – you need this book!

TinyDB stores data on your smart phone or tablet and is a primary way for App Inventor apps to save data, even when the app is no longer running or if the device is turned off.

TinyWebDB is similar to TinyDB, but stores your data on a remote server in the network cloud.

Multiple apps can share a TinyWebDB database, plus you can update the content of your TinyWebDB using just a web browser. This means you can distribute an app whose content can change over time – just by changing the values in TinyWebDB.

A big challenge is the need to set up a TinyWebDB server – this book shows how to do that through free services offered by Google.

Fusion Tables provide a powerful, cloud-based database system for App Inventor apps. Creating, retrieving, updating and deleting data is done using the industry standard Structured Query Language or SQL. Fusion Tables reside in the Google network cloud – this book shows you how to set up and configure Fusion Tables for you own apps using free services of Google. As your app requirements grow, Google’s cloud can provide low cost servers and bandwidth for your needs.

Underneath the Android OS user interface, there is a file system, similar to the file system found on Windows or Mac OS X. With App Inventor your apps can write and read data from files, and if using the special “CSV” format, App Inventor data can be shared with many spreadsheet programs. This book shows you how to create, use and access data files, and how to convert data to and from the CSV format.

Over 28,000 words. Amazon’s page count is 322 pages. Over 250 screen shots and illustrations. Numerous sample programs and code.

App Inventor 2: Databases and Files – Table of Contents
1 – Introduction
2 – Using the TinyDB database
3 – Implementing Records Using Lists in TinyDB
4 – Simulating Multiple TinyDB Databases
5 – How to Use Multiple Tags in TinyDB
6 – Introduction and Setup: TinyWebDB
7 – Managing TinyWebDB in the Cloud
8 – Programming for TinyWebDB – Demo 1
9 – Adding a Tags List to TinyWebDB – Demo 2
10 – Handling Multiple Users with TinyWebDB – Demo 3
11 – Implementing a Student Quiz Application using TinyWebDB
12 – Introduction to Fusion Tables
13 – Developing Your Fusion Table App
14 – Using Text Files in App Inventor

New Linux OS version designed for Android & App Inventor app development

The Appril release of Quirky Linux includes the Android SDK (Software Development Kit), Android Studio, App Inventor, Oracle JDK (Java Development Kit), and LiveCode tools, as well as all of their dependencies, together with the JWM (Joe’s Window Manager) and ROX, providing one of the lightest environments for Android app developers.

“The intention is to have out-of-the-box, just-click-and-get-going Android app development, catering for total non-programmers with App Inventor, through intermediate with LiveCode, to hard-core coders with Android Studio,” says Barry Kauler, Puppy Linux creator.

Source: Puppy Linux’s Sister Quirky 7.1 Distro Arrives with Tools for Android App Developers

It actually runs the App Inventor system on the computer – does not require access to appinventor.mit.edu.

Download here (its free, of course). I have not tried this yet but would be interested to hear reports from users!