Accessibility Map

Filtering By Distance

Great! You now have a procedure that can work out the distance between two addresses. Next you’ll add this to your when FireBase.GotValue function.

For this you of course need two addresses: the address of the accessible place and your address (the address of the app user).

  • First you should get your current location. As you will be using this value multiple times, it’s a good idea to store it as a variable. Add an initialize global name to block, change its name to currentLocation, and set it to an empty text block.

  • In the when ListOfPlaces.Initialize block, add a set global currentLocation to block and connect it with a get LocationSensor.CurrentAddress block.

But what if the user’s location is unavailable? To cover this possibility, you need to do a check before setting the currentLocation variable.

  • Put an if then block into when ListOfPlaces.Initialize and move the set global currentLocation code into the then.

  • Find the LocationSensor.HasLongitudeLatitude block and attach it to the if:

Now you are ready to use the procedure you made to get the distance.

  • Insert an initialize local name to block (the one with a top attachment) into the then in your when FireBase.GotValue, and change name to distance.

  • You only want to use the distance formula if you know the user’s location, so connect an if then else block (the one that has a side attachment). To the if, attach three blocks: not (Logic), is empty (Text), and get global currentLocation.

  • Connect a call distanceBetween block to the then. If the currentLocation is blank, you will just show all the places, so place a 0 Math block in the else to return zero as the distance.

  • For one of the parameters (values that you pass to the function) of the call distanceBetween, attach a get global currentLocation block. For the other parameter, attach a get value block (remember this contains the address of the place you got from Firebase).

  • Inside the initialize local distance to block, add an if then block.

You are now going to check whether the distance is less than 5km.

  • Get a < block and a a 0 block from the Math section.

  • Put a get distance into the first input in the < block, and the 0 block into the second input. Set the 0 block to 5.

  • Plug the < block into the if then block.

  • Move the add items to list block so it is inside the then statement of the if then block.

  • If everything has gone correctly, it should look like this:

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