topic How do I free/unload local tile cache file? in .NET Maps SDK Questions

How do I free/unload local tile cache file?

ViktorSafar — Thu, 09 Feb 2023 11:46:54 GMT

I have an offline device running a WPF app using VectorTileCache to add ArcGISVectorTiledLayer to the app's map. VectorTileCache loads a .vtpk file from the device's disk.

I have built capability to download a new version of the .vtpk file from a remote source and I would like to reload the ArcGISVectorTiledLayer when the new file is ready.

When I try to replace the old vtpk with the new one, I get an error that the file is in use:

System.IO.IOException: 'The process cannot access the file 'C:\temp\GeocacheKystVector.vtpk' because it is being used by another process.'

The ArcGISVectorTiledLayer that refers the vtpk is an item in Basemap.BaseLayers. I remove the item, run GC, but still get that IOException.

How do I unload the package?

Re: How do I free/unload local tile cache file?

AndyWeis — Sat, 18 Feb 2023 04:30:37 GMT

Hi @ViktorSafar, could you please provide the code used to do this?

Re: How do I free/unload local tile cache file?

ViktorSafar — Fri, 17 Mar 2023 13:52:04 GMT

Hi @AndyWeis

While attempting to make a PoC about this, it turned out I was overcomplicating things.

What I was doing:

load a VTPK file (eg. mymap.vtpk)
download new package to TEMP file
delete current VTPK file (mymap.vtpk)
move TEMP file to mymap.vtpk

The IO Exception was of course happening in step 3 as the file was being used by the application

I have now changed it to just directly copy the TEMP file into the current VTPK file

File.Copy(_newPackageFile, _packageFile, overwrite: true);

and am getting no exceptions.

However, I am uncertain if this works as intended - aka the map is updated with the new package, as this is hard to check (basemap layers are big 🙂 ).

To test it, I have been using 2 VTPK packages, each containing a different map (visually different):

mymap.vtpk (contains a coastal map of Norway)
greytone.vtpk (contains a grey tone map of Norway)

I load package1 (mymap.vtpk) into the map on startup, then on button click I copy package2 file into package1 file. No error. The only thing I notice is that the map stops rendering details:

I realize this might not be the best way to test it due to the packages containing different maps.

What would be the recommended way to update a local package (that is loaded into the application) while the application is running? Could it be as simple as this?

File.Copy(_newPackageFile, _packageFile, overwrite: true); Map.Basemap.BaseLayers.First().RetryLoadAsync(); // find the appropriate base layer