@Override
    public Cursor swapCursor(Cursor c) {
        // super.swapCursor() will notify observers before we have
        // a valid mapping, make sure we have a mapping before this
        // happens
        findColumns(c, mOriginalFrom);
        return super.swapCursor(c);
    }
Create a map from an array of strings to an array of column-id integers in cursor c.
If c is null, the array will be discarded.

@param c the cursor to find the columns from
@param from the Strings naming the columns of interest
third_party/DragSortListView/src/com/mobeta/android/dslv/SimpleDragSortCursorAdapter.java