getting the event.location value into a variable when calling a location handler function

Hardware (GPS, accelerometer, etc.)
#1

Hi, I’m hoping for your experience to fix my error.

What I want to achieve is this:

At phone start, phone locates lattitude and longitude, these then get concatenated into a variable, which is then used later in the code to construct a url.

I am so close but have hit a wall.  A code snippet below:

local latlongdisplay = display.newText( "-", 100, 50, native.systemFont, 16 ) locationHandler = function( event ) if ( event.errorCode ) then native.showAlert( "GPS Location Error", event.errorMessage, {"OK"} ) print( "Location error: " .. tostring( event.errorMessage ) ) else local latlongtext = string.format( '%.4f', event.latitude ) .. "," .. string.format( '%.4f', event.longitude ) latlongdisplay.text = latlongtext end return latlongtext end Runtime:addEventListener( "location", locationHandler ) if latlongtext == nil then print( " it was nil" ) else print( "it was: " .. latlongtext ) end

so… this works fine to populate the display.newText object, and I see it on screen… however, the actual local variable of latlongtext remains nil.

Can someone please advise how I reliably get the value of latlongtext OUT of the function, so I can use it elsewhere.  

ps, I know it’s a local variable inside the if/then clause, but I’d prefer to not have to use a global variable, when there is likely a better method.

thanks all

#2

You’ve got a lot going on here, but the basic way you would resolve this, is to scope your  latlongtext variable higher in your module/scene, update the value and don’t create it in the Runtime listener, and move your print() call to be within your Runtime listener. Something like this:

local latlongdisplay = display.newText( "-", 100, 50, native.systemFont, 16 ) local latlongtext locationHandler = function( event ) if ( event.errorCode ) then native.showAlert( "GPS Location Error", event.errorMessage, {"OK"} ) print( "Location error: " .. tostring( event.errorMessage ) ) else latlongtext = string.format( '%.4f', event.latitude ) .. "," .. string.format( '%.4f', event.longitude ) latlongdisplay.text = latlongtext end if latlongtext == nil then print( " it was nil" ) else print( "it was: " .. latlongtext ) end end Runtime:addEventListener( "location", locationHandler )

Untested so YMMV.

#3

thanks very much, that makes sense, I’ll do more testing.

#4

next question. I want to use the value for latlongtext further in my code, but no matter what I try , it is always nil.

i.e After I call this line 

Runtime:addEventListener( “location”, locationHandler )

I want to use the variable latlongtext in the construction of a url. It appears to me that the return value is passed back to the caller of the locationHandler function, which in this case is the Runtime:addEventListener

so… can you advise the best way to get the lat and long INTO variable that I can use elsewhere?

#5

You’ve got a lot going on here, but the basic way you would resolve this, is to scope your  latlongtext variable higher in your module/scene, update the value and don’t create it in the Runtime listener, and move your print() call to be within your Runtime listener. Something like this:

local latlongdisplay = display.newText( "-", 100, 50, native.systemFont, 16 ) local latlongtext locationHandler = function( event ) if ( event.errorCode ) then native.showAlert( "GPS Location Error", event.errorMessage, {"OK"} ) print( "Location error: " .. tostring( event.errorMessage ) ) else latlongtext = string.format( '%.4f', event.latitude ) .. "," .. string.format( '%.4f', event.longitude ) latlongdisplay.text = latlongtext end if latlongtext == nil then print( " it was nil" ) else print( "it was: " .. latlongtext ) end end Runtime:addEventListener( "location", locationHandler )

Untested so YMMV.

#6

thanks very much, that makes sense, I’ll do more testing.

#7

next question. I want to use the value for latlongtext further in my code, but no matter what I try , it is always nil.

i.e After I call this line 

Runtime:addEventListener( “location”, locationHandler )

I want to use the variable latlongtext in the construction of a url. It appears to me that the return value is passed back to the caller of the locationHandler function, which in this case is the Runtime:addEventListener

so… can you advise the best way to get the lat and long INTO variable that I can use elsewhere?