uwp file open picker
// Create the picker object and set options
var openPicker = new Windows.Storage.Pickers.FileOpenPicker();
openPicker.viewMode = Windows.Storage.Pickers.PickerViewMode.thumbnail;
openPicker.suggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.picturesLibrary;
// Users expect to have a filtered view of their folders depending on the scenario.
// For example, when choosing a documents folder, restrict the filetypes to documents for your application.
openPicker.fileTyp