Question

FileOpenPicker openPicker = new FileOpenPicker();
openPicker.ViewMode = PickerViewMode.Thumbnail;
openPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
openPicker.FileTypeFilter.Add(".jpg");
openPicker.FileTypeFilter.Add(".jpeg");
openPicker.FileTypeFilter.Add(".png");

StorageFile file = await openPicker.PickSingleFileAsync();
if (file != null)
{
    // Application now has read/write access to the picked file
    OutputTextBlock.Text = "Picked photo: " + file.Name;
}
else
{
    OutputTextBlock.Text = "Operation cancelled.";
}

How do I add openPicker.FileTypeFilter.Add(".*"); means show all file types in file picker?

Answer 1

You are almost there.. the correct syntax is openPicker.FileTypeFilter.Add("*");

From the FileTypeFilter documentation:

The File picker sample demonstrates how to show files of any type in
the file picker for the user to pick from.

Where the code from the sample:

FileOpenPicker openPicker = new FileOpenPicker();
openPicker.ViewMode = PickerViewMode.List;
openPicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary;
openPicker.FileTypeFilter.Add("*");