this is my first mobile app using the MIT App inventor (appinventor.mit.edu).
The purpose of the app is to localize the user, show current position on map and send it via text message.
On the first screenshot you can see the elements on the screen.
Here is the "code".
It consist of several blocks which we will have a look in next steps.
The First block is response for transfering geolocation data from location sensor to screen controls.
It also resolves current address based on the user location.
Step 3: Map Update
The second block is event handler fpr the refresh button.
It updates the map with the current user position.
Step 4: Send SMS
The 3rd block formats current address, longitude and latitude to a message and initates a new text message.