Location works strangely the second time

Hardware (GPS, accelerometer, etc.)
#1

Good morning.

User taps a button.

I install an event listener to figure out where (geographically) I am:

Runtime:addEventListener(“location”,locationHandler)

LocationHandler() gets called correctly. I figure out where I am and do some other stuff.

Then, I remove the listener:

Runtime:removeEventListener(“location”,locationHandler)

Then user taps same button. LocationHandler is invoked immediately as before. Some minutes later things happen. When they happen, they do the right stuff, but a five-ten minute delay?

Off to give blood now.

Thank you.

-Bob Gordon

#2

I don’t have much familiarity with this, but why not just keep the event listener active? Perhaps use a switch in locationHandler so the code only executes when necessary.

#3

I have posted an simple project that demonstrates the issue in “Location Handler Appears to Stop.” Please look there.

#4

The reason I want to turn the handler off is that continually refreshing the location is a battery drain.

#5

It takes time after starting up the location handler functions to acquire the GPS satellites. Five minutes seems kinda long though. It should fire up in 10-30 seconds worse case. Today, Apple gives you the option to only have the GPS running in the foreground, so it’s better on the battery than when running in the background.

I didn’t see a link to your test project.

Rob

#6

Rob,

Test project is under this topic: 

Location Handler Appears to Stop

#7

We prefer you to only have one thread open for discussing an issue.

#8

The thread with the downloadable link for anyone wanting to look at this is:

https://forums.coronalabs.com/topic/63076-location-handler-appears-to-stop/

I will be locking that thread, please continue the conversation here.

Rob

#9

Good morning. I have modified the example program. There is now a button “Timed Location”. Tap it. Every 5 seconds it turns on the location handler, which turns off after a second. After 2 - 4 times, the handler stops responding.

-Bob

#10

I’ve not looked at your modified one, but the one you sent yesterday stopped working in the sim after a few presses of the button. I made the following changes and now it doesn’t stop working:

local removeHandler -- forward declare for the remove function. You need to know about it -- before you define it. local locationHandler = function( event ) log.trace("locationHandler") if ( event.errorCode ) then native.showAlert( "GPS Location Error", event.errorMessage, {"OK"} ) else if delegate then removeHandler() -- call the remove handler here after you've handle the event -- this might even be safer dropped into a short timer: -- timer.performWithDelay(10, removeHandler, 1 ) delegate(event) end end end removeHandler = function() -- since this was forward declared, you have to use the anonymous function syntax log.trace("removeHandler") Runtime:removeEventListener( "location", locationHandler ) end local function getLocation() Runtime:addEventListener("location",locationHandler) --timer.performWithDelay(1000,removeHandler) -- take it off of the timer end

Give that a try.

#11

Rob, 

Thank you.

I also came up with a solution: I used a mapview. Since the project does not require the user to actually use the map, I placed a small map off the screen and called getUserLocation. When I get the location I call removeSelf on the map.

I’ll try your suggestion, too. I’m still doing lots of learning.

-Bob Gordon

#12

I don’t have much familiarity with this, but why not just keep the event listener active? Perhaps use a switch in locationHandler so the code only executes when necessary.

#13

I have posted an simple project that demonstrates the issue in “Location Handler Appears to Stop.” Please look there.

#14

The reason I want to turn the handler off is that continually refreshing the location is a battery drain.

#15

It takes time after starting up the location handler functions to acquire the GPS satellites. Five minutes seems kinda long though. It should fire up in 10-30 seconds worse case. Today, Apple gives you the option to only have the GPS running in the foreground, so it’s better on the battery than when running in the background.

I didn’t see a link to your test project.

Rob

#16

Rob,

Test project is under this topic: 

Location Handler Appears to Stop

#17

We prefer you to only have one thread open for discussing an issue.

#18

The thread with the downloadable link for anyone wanting to look at this is:

https://forums.coronalabs.com/topic/63076-location-handler-appears-to-stop/

I will be locking that thread, please continue the conversation here.

Rob

#19

Good morning. I have modified the example program. There is now a button “Timed Location”. Tap it. Every 5 seconds it turns on the location handler, which turns off after a second. After 2 - 4 times, the handler stops responding.

-Bob

#20

I’ve not looked at your modified one, but the one you sent yesterday stopped working in the sim after a few presses of the button. I made the following changes and now it doesn’t stop working:

local removeHandler -- forward declare for the remove function. You need to know about it -- before you define it. local locationHandler = function( event ) log.trace("locationHandler") if ( event.errorCode ) then native.showAlert( "GPS Location Error", event.errorMessage, {"OK"} ) else if delegate then removeHandler() -- call the remove handler here after you've handle the event -- this might even be safer dropped into a short timer: -- timer.performWithDelay(10, removeHandler, 1 ) delegate(event) end end end removeHandler = function() -- since this was forward declared, you have to use the anonymous function syntax log.trace("removeHandler") Runtime:removeEventListener( "location", locationHandler ) end local function getLocation() Runtime:addEventListener("location",locationHandler) --timer.performWithDelay(1000,removeHandler) -- take it off of the timer end

Give that a try.