Kotlin - 位置跟踪问题

Question

I must have to take latitude and longitude of the user when user first time open an application.

So far, I have done as below :

Necessary Variables :

 //Location Utils below :
    private lateinit var fusedLocationClient: FusedLocationProviderClient
    private lateinit var lastLocation: Location
    private lateinit var currentLatLng: LatLng

On Button Click : Checking the permission for the location, if has permission calling method named onLocationGranted() else asking for the location permission.

if (EasyPermissions.hasPermissions(
                        mContext,
                        FilePickerConst.PERMISSIONS_FINE_LOCATION
                    )
                ) {
                    onLocationGranted()
                } else {
                    // Ask for one permission
                    EasyPermissions.requestPermissions(
                        this,
                        getString(R.string.permission_location),
                        Constant.MultiMediaRequestCode.LOCATION_PERMISSION,
                        FilePickerConst.PERMISSIONS_FINE_LOCATION
                    )
                }

Below is the method onLocationGranted() : Here, Initializing LocationManager, Checking that GPS is on or not. If GPS on or enabled, taking location which is done in method named : getAndSaveCurrentLocation() . If, GPS is off or not enabled calling the method named buildAlertMessageNoGps()

val manager = mContext.getSystemService(Context.LOCATION_SERVICE) as LocationManager    
//If GPS is not Enabled..
if (!manager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
   buildAlertMessageNoGps()
} else {
   getAndSaveCurrentLocation()
}

Method getAndSaveCurrentLocation() is as below : In which I am taking location using fusedapi.

private fun getAndSaveCurrentLocation() {
    try {
        fusedLocationClient =
            LocationServices.getFusedLocationProviderClient(mContext as AppBaseActivity)

        fusedLocationClient.lastLocation.addOnSuccessListener(mContext as AppBaseActivity) { location ->
            // Got last known location. In some rare situations this can be null.
            if (location != null) {
                lastLocation = location
                currentLatLng = LatLng(location.latitude, location.longitude)
                if (currentLatLng != null &&
                    currentLatLng.latitude != null &&
                    currentLatLng.longitude != null
                ) {
                    sharedPreferenceManager?.setStringData(
                        Constant.PrefKey.userLatitude,
                        "" + currentLatLng.latitude
                    )

                    sharedPreferenceManager?.setStringData(
                        Constant.PrefKey.userLongitude,
                        "" + currentLatLng.longitude
                    )
                }

            }
            (mContext as AppBaseActivity).supportFragmentManager.popBackStack()
            (activity as AppBaseActivity).addFragmentToRoot(
                DashboardFragmentNew.newInstance(),
                false
            )
        }
    } catch (e: Exception) {
        e.printStackTrace()
    }
}

Method buildAlertMessageNoGps() is as below : If GPS is off then, I am calling this method.

private fun buildAlertMessageNoGps() {
        val builder = AlertDialog.Builder(mContext)
        builder.setMessage("Your GPS seems to be disabled, do you want to enable it?")
            .setCancelable(false)
            .setPositiveButton("Yes", object : DialogInterface.OnClickListener {
                override fun onClick(dialog: DialogInterface, id: Int) {
                    startActivity(Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS))
                }
            })
            .setNegativeButton("No", object : DialogInterface.OnClickListener {
                override fun onClick(dialog: DialogInterface, id: Int) {
                    dialog.cancel()
                }
            })
        val alert = builder.create()
        alert.show()
    }

Now, the above method opens the settings to turn on GPS.

My question is : Suppose user turns on GPS, and coming back to screen, How can I get location then ? Or If user not turning on GPS there, in that case How can I take location?

Thanks.

Answer 1

Suppose user turns on GPS, and coming back to screen, How can I get location then ?

You will get a call back to onActivityReenter similar to onActivityResult. So Override that method and call getAndSaveCurrentLocation() there.