c# - How to get available space on Storage Device -

i'm working on windows store app (windows 8.1, using vs2012), , i'm having trouble retrieving available/used space specific storage folder, retrieved storage device. clear, app meant run on desktop, , exchange files usb devices connected through storage device api.

this have until now:

storagefolder folder = windows.devices.portable.storagedevice.fromid(phoneid);  uint64[] info = new uint64[] {}; var properties = await folder.properties.retrievepropertiesasync(     new string[] { "system.freespace", "system.capacity" });  if (properties.containskey("system.freespace") && properties.containskey("system.freespace")) {   info = new uint64[] {     (uint64) properties["system.freespace"],     (uint64) properties["system.capacity"]   }; } return info; 

but no success, 'info' empty array. ideas?

i've found out doing wrong. storagefolder object representing phone connected desktop. if 1 goes through explorer , access phone folder, see 'inner folders', actual storage folders phone (eg. internal storage, sd card, etc).

the correct way phones access subfolders (ie. each internal storage). code i'm using now:

storagefolder folder = windows.devices.portable.storagedevice.fromid(phoneid);  var data = new list<tuple<string, uint64[]>> { }; ireadonlylist<storagefolder> subfolders = await folder.getfoldersasync(); foreach (storagefolder subfolder in subfolders) {   var props = await subfolder.properties.retrievepropertiesasync(     new string[] { "system.freespace", "system.capacity" });   if (props.containskey("system.freespace") && props.containskey("system.capacity"))   {     data.add(tuple.create(       subfolder.name,       new uint64[] {         (uint64) props["system.freespace"],         (uint64) props["system.capacity"]     }));   } } return data;