public async void ZamenaPic(string textNaZamenu1, StorageFile file)
        {
            if (file != null)
            {
                using (IRandomAccessStream fileStream = await file.OpenAsync(Windows.Storage.FileAccessMode.Read))
                {
                    string textToFind = textNaZamenu1;

                    if (textToFind != null)
                    {
                        RichEditBox richEditBox = new RichEditBox();
                        richEditBox.Document.SetText(Windows.UI.Text.TextSetOptions.FormatRtf, stringRich);
                        ITextRange searchRange = richEditBox.Document.GetRange(0, 0);
                        if (searchRange.FindText(textToFind, TextConstants.MaxUnitCount, FindOptions.Word) > 0)
                        {
                            await new MessageDialog(searchRange.EndPosition.ToString()).ShowAsync();
                            // searchRange.SetText(TextSetOptions.FormatRtf, zamena);
                            BitmapImage image = new BitmapImage();

                            await image.SetSourceAsync(fileStream);

                            searchRange.InsertImage(100, 100, 0, VerticalCharacterAlignment.Baseline, "img", fileStream);
                        }
                        string ss = String.Empty;
                        richEditBox.TextDocument.GetText(Windows.UI.Text.TextGetOptions.FormatRtf, out ss);
                        stringRich = ss;
                    }
                }
            }
        }