Blocks and Component Reference
This Blocks and Component Reference explains App Inventor’s important blocks and components and those not used or explained in the main projects throughout this book. This is not a comprehensive reference. Refer to the index to discover where you can find more information on any component not referenced here. App Inventor is growing and improving all the time. Be sure and check out the online documentation for App Inventor at
All of the drawers for the built-in App Inventor blocks are located on the Built-In blocks tab of the Blocks Editor. The following is not a comprehensive list of drawers or blocks. Each drawer that is listed has a select few important or unreferenced blocks. Each block is named and then explained and demonstrated.
The Definitions drawer
The following blocks can be found in the Definitions drawer.
ProcedureWithResult block allows you to create a subroutine of blocks to which you can pass data using arguments. You can then have blocks in the
ProcedureWithResult process the data and return the output to the block that initially called the procedure. The arguments are optional.
When you create a
call block with the same name is created in the My Definitions drawer. The
call block has sockets with names to match any
name blocks placed into the
When you place a
name block in an