MapView LocationHandler Event

Getting Started Newbie Questions
#1

hello guys,

i created and finished an App almost similar to Uber, but a little bit different…

it consists of 2 apps:

with first app you place an order through a menu

with second app the nearest driver gets your order and delivers it

the app is very smooth and very quick…

i have 2 problems though!!

Problem1:

i’m not sure i’m using the LocationHandler event for mapview correctly, as everytime i’m removing the current mapview, and loading a new one to get an updated GPS location, is that correct? or can the same eventHandler refresh automatically

Problem2:

how can i get more info from the returned GPS Coordinates like city or country name

Thanks

Tariq

#2

Problem 2:

For more information, use Google services to look up the info on the GPS coordinates.  It has been a long time since I did this, but I think you want to use the ‘Google Places’ API: https://developers.google.com/places/

#3

I dug through an old project of mine.  You will have to research this yourself, but back when I wrote this project (2015-ish)  you could build a request for nearby parks (what I was doing in the app) like this:

 -- -- Create Places Query -- headers = {} headers["Content-Type"] = "application/json" headers["Accept-Language"] = "en-US" body = "" local params = {} params.headers = headers params.body = body local requestString -- 1. Configure search type requestString = "https://maps.googleapis.com/maps/api/place/nearbysearch/json" -- 2. Add lat/long requestString = requestString .. "?location=" .. public.latitude .. "," .. public.longitude --requestString = requestString .. "?location=" .. 45.324226 .. "," .. -122.582864 -- 3. Add radius requestString = requestString .. "&radius=" .. searchRadius -- 4. Add 'park' to the types search (Tip: | is separator for multiple types) requestString = requestString .. "&types=park" -- Multi-Types example =\> requestString = requestString .. "&types=type1|type2|type3|etc" -- 5. Add sensor requestString = requestString .. "&sensor=false" -- 6. Add key requestString = requestString .. "&key=" .. GooglePlacesAPIKey --print("\n\n" .. requestString) -- Sample searches that produce results -- DEBUG ONLY - Known working 'nearby' request string to test in case you have issues. -- UNCOMMENT THIS TO OVERRIDE BUILT-UP REQUEST STRING -- requestString = "https://maps.googleapis.com/maps/api/place/nearbysearch/json?location=45.324226,-122.582864&radius=5000&types=park&sensor=false&key=" .. GooglePlacesAPIKey print("Request string:\n") print("requestString\n" ) network.request( requestString, "POST", placesNetworkListener, params)

Clearly, your request would be different, but it would be similar in format.

The listener looked kinda like this:

-- == -- placesNetworkListener - Callback that handles Google Places Search Results. -- == local function placesNetworkListener( event ) local foundPark = false local foundDistance = tonumber(searchRadius)/1000 local nearestPark = math.huge local nearestParkName = "" local message if ( event.isError ) then print( "Network error!") return else --print ( "RESPONSE: " .. event.response ) local response = json.decode( event.response ) if(response) then print("Responses --\> " ..#response.results ) if(response.results) then for i = 1, #response.results do local res = response.results[1] if( res.name ) then --print( res.name .. "\n" ) end if( res.geometry and res.geometry.location ) then local lat = tostring(res.geometry.location.lat) local lng = tostring(res.geometry.location.lng) lat = lat:lpad(#lng) local deltaLat = tostring(round(tonumber(res.geometry.location.lat) - tonumber(public.latitude), 6)) local deltaLng = tostring(round(tonumber(res.geometry.location.lng) - tonumber(public.longitude), 6)) local deltaLen = tostring(ssk.math2d.length( tonumber(res.geometry.location.lat) - tonumber(public.latitude), tonumber(res.geometry.location.lng) - tonumber(public.longitude) )) deltaLat = deltaLat:lpad(9) deltaLng = deltaLng:lpad(9) deltaLen = deltaLen:lpad(9) local latStr = lat .. " (delta: " .. deltaLat .. ")" local lngStr = lng .. " (delta: " .. deltaLng .. ")" --print( " public.latitude: " .. latStr .. "\n" ) --print( " public.longitude: " .. lngStr .. "\n" ) --print( " delta len: " .. deltaLen .. "\n\n" ) -- Now, check to see if local lat1 = tonumber(public.latitude) local lng1 = tonumber(public.longitude) local lat2 = tonumber(res.geometry.location.lat) local lng2 = tonumber(res.geometry.location.lng) local dist = math.haversine\_dist( lat1, lng1, lat2, lng2 ) if( dist \<= foundDistance ) then foundPark = true end if( foundPark and dist \< nearestPark) then nearestPark = dist nearestParkName = res.name print('i:', i, dist, foundDistance, nearestParkName, foundDistance ) end end end end end end end
#4

Problem 2:

For more information, use Google services to look up the info on the GPS coordinates.  It has been a long time since I did this, but I think you want to use the ‘Google Places’ API: https://developers.google.com/places/

#5

I dug through an old project of mine.  You will have to research this yourself, but back when I wrote this project (2015-ish)  you could build a request for nearby parks (what I was doing in the app) like this:

 -- -- Create Places Query -- headers = {} headers["Content-Type"] = "application/json" headers["Accept-Language"] = "en-US" body = "" local params = {} params.headers = headers params.body = body local requestString -- 1. Configure search type requestString = "https://maps.googleapis.com/maps/api/place/nearbysearch/json" -- 2. Add lat/long requestString = requestString .. "?location=" .. public.latitude .. "," .. public.longitude --requestString = requestString .. "?location=" .. 45.324226 .. "," .. -122.582864 -- 3. Add radius requestString = requestString .. "&radius=" .. searchRadius -- 4. Add 'park' to the types search (Tip: | is separator for multiple types) requestString = requestString .. "&types=park" -- Multi-Types example =\> requestString = requestString .. "&types=type1|type2|type3|etc" -- 5. Add sensor requestString = requestString .. "&sensor=false" -- 6. Add key requestString = requestString .. "&key=" .. GooglePlacesAPIKey --print("\n\n" .. requestString) -- Sample searches that produce results -- DEBUG ONLY - Known working 'nearby' request string to test in case you have issues. -- UNCOMMENT THIS TO OVERRIDE BUILT-UP REQUEST STRING -- requestString = "https://maps.googleapis.com/maps/api/place/nearbysearch/json?location=45.324226,-122.582864&radius=5000&types=park&sensor=false&key=" .. GooglePlacesAPIKey print("Request string:\n") print("requestString\n" ) network.request( requestString, "POST", placesNetworkListener, params)

Clearly, your request would be different, but it would be similar in format.

The listener looked kinda like this:

-- == -- placesNetworkListener - Callback that handles Google Places Search Results. -- == local function placesNetworkListener( event ) local foundPark = false local foundDistance = tonumber(searchRadius)/1000 local nearestPark = math.huge local nearestParkName = "" local message if ( event.isError ) then print( "Network error!") return else --print ( "RESPONSE: " .. event.response ) local response = json.decode( event.response ) if(response) then print("Responses --\> " ..#response.results ) if(response.results) then for i = 1, #response.results do local res = response.results[1] if( res.name ) then --print( res.name .. "\n" ) end if( res.geometry and res.geometry.location ) then local lat = tostring(res.geometry.location.lat) local lng = tostring(res.geometry.location.lng) lat = lat:lpad(#lng) local deltaLat = tostring(round(tonumber(res.geometry.location.lat) - tonumber(public.latitude), 6)) local deltaLng = tostring(round(tonumber(res.geometry.location.lng) - tonumber(public.longitude), 6)) local deltaLen = tostring(ssk.math2d.length( tonumber(res.geometry.location.lat) - tonumber(public.latitude), tonumber(res.geometry.location.lng) - tonumber(public.longitude) )) deltaLat = deltaLat:lpad(9) deltaLng = deltaLng:lpad(9) deltaLen = deltaLen:lpad(9) local latStr = lat .. " (delta: " .. deltaLat .. ")" local lngStr = lng .. " (delta: " .. deltaLng .. ")" --print( " public.latitude: " .. latStr .. "\n" ) --print( " public.longitude: " .. lngStr .. "\n" ) --print( " delta len: " .. deltaLen .. "\n\n" ) -- Now, check to see if local lat1 = tonumber(public.latitude) local lng1 = tonumber(public.longitude) local lat2 = tonumber(res.geometry.location.lat) local lng2 = tonumber(res.geometry.location.lng) local dist = math.haversine\_dist( lat1, lng1, lat2, lng2 ) if( dist \<= foundDistance ) then foundPark = true end if( foundPark and dist \< nearestPark) then nearestPark = dist nearestParkName = res.name print('i:', i, dist, foundDistance, nearestParkName, foundDistance ) end end end end end end end