Create, read, and edit Excel files in UWP

10 Jul 202324 minutes to read

Syncfusion Excel library for UWP platform can be used to create, read, edit Excel files. This also convert Excel files to PDF.

Create a simple Excel report

The below steps illustrates creating an simple Invoice formatted Excel document in UWP application.

Step 1: Create a new C# Blank App (Universal Windows) project.

Create UWP application in Visual Studio

Step 2: Install the Syncfusion.XlsIO.UWP NuGet package as reference to your .NET Framework applications from NuGet.org.

Add XlsIO reference to the project

NOTE

Starting with v16.2.0.x, if you reference Syncfusion assemblies from trial setup or from the NuGet feed, you also have to add “Syncfusion.Licensing” assembly reference and include a license key in your projects. Please refer to this link to know about registering Syncfusion license key in your applications to use our components.

Step 3: Add a new button in the MainPage.xaml as shown below.

<Page
       x:Class="GettingStarted_UWP.MainPage"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
       xmlns:local="using:GettingStarted_UWP"
       xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
       xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
       mc:Ignorable="d"
       Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
   
       <Grid>
           <Button x:Name="button" Content="Create Document" Click="OnButtonClicked" HorizontalAlignment="Center" VerticalAlignment="Center"/>
       </Grid>
   </Page>

Step 4: Include the following namespaces in the MainPage.xaml.cs file.

using Syncfusion.XlsIO;
   using Windows.Storage.Pickers;
   using Windows.Storage;
   using Windows.UI;
Imports Syncfusion.XlsIO
   Imports Windows.Storage.Pickers
   Imports Windows.Storage
   Imports Windows.UI

Step 5: Include the below code snippet in the click event of the button in MainPage.xaml.cs, to create an Excel file and save the Excel document as a physical file and open the file for viewing.

//Create an instance of ExcelEngine.
   using (ExcelEngine excelEngine = new ExcelEngine())
   {
     IApplication application = excelEngine.Excel;
     application.DefaultVersion = ExcelVersion.Xlsx;
   
     //Create a workbook with a worksheet
     IWorkbook workbook = application.Workbooks.Create(1);
   
     //Access first worksheet from the workbook instance.
     IWorksheet worksheet = workbook.Worksheets[0];
     Assembly executingAssembly = typeof(MainPage).GetTypeInfo().Assembly;
     Stream inputStream = executingAssembly.GetManifestResourceStream("GettingStarted_UWP.AdventureCycles-Logo.png");
   
     //Add a picture
     IPictureShape shape = worksheet.Pictures.AddPicture(1, 1, inputStream, 20, 20);
   
     //Disable gridlines in the worksheet
     worksheet.IsGridLinesVisible = false;
   
     //Enter values to the cells from A3 to A5
     worksheet.Range["A3"].Text = "46036 Michigan Ave";
     worksheet.Range["A4"].Text = "Canton, USA";
     worksheet.Range["A5"].Text = "Phone: +1 231-231-2310";
   
     //Make the text bold
     worksheet.Range["A3:A5"].CellStyle.Font.Bold = true;
   
     //Merge cells
     worksheet.Range["D1:E1"].Merge();
   
     //Enter text to the cell D1 and apply formatting.
     worksheet.Range["D1"].Text = "INVOICE";
     worksheet.Range["D1"].CellStyle.Font.Bold = true;
     worksheet.Range["D1"].CellStyle.Font.RGBColor = ColorHelper.FromArgb(0, 42, 118, 189);
     worksheet.Range["D1"].CellStyle.Font.Size = 35;
   
     //Apply alignment in the cell D1
     worksheet.Range["D1"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignRight;
     worksheet.Range["D1"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop;
   
     //Enter values to the cells from D5 to E8
     worksheet.Range["D5"].Text = "INVOICE#";
     worksheet.Range["E5"].Text = "DATE";
     worksheet.Range["D6"].Number = 1028;
     worksheet.Range["E6"].Value = "12/31/2018";
     worksheet.Range["D7"].Text = "CUSTOMER ID";
     worksheet.Range["E7"].Text = "TERMS";
     worksheet.Range["D8"].Number = 564;
     worksheet.Range["E8"].Text = "Due Upon Receipt";
   
     //Apply RGB backcolor to the cells from D5 to E8
     worksheet.Range["D5:E5"].CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189);
     worksheet.Range["D7:E7"].CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189);
   
     //Apply known colors to the text in cells D5 to E8
     worksheet.Range["D5:E5"].CellStyle.Font.Color = ExcelKnownColors.White;
     worksheet.Range["D7:E7"].CellStyle.Font.Color = ExcelKnownColors.White;
   
     //Make the text as bold from D5 to E8
     worksheet.Range["D5:E8"].CellStyle.Font.Bold = true;
   
     //Apply alignment to the cells from D5 to E8
     worksheet.Range["D5:E8"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
     worksheet.Range["D5:E5"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
     worksheet.Range["D7:E7"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
     worksheet.Range["D6:E6"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop;
   
     //Enter value and applying formatting in the cell A7
     worksheet.Range["A7"].Text = "  BILL TO";
     worksheet.Range["A7"].CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189);
     worksheet.Range["A7"].CellStyle.Font.Bold = true;
     worksheet.Range["A7"].CellStyle.Font.Color = ExcelKnownColors.White;
   
     //Apply alignment
     worksheet.Range["A7"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft;
     worksheet.Range["A7"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
   
     //Enter values in the cells A8 to A12 
     worksheet.Range["A8"].Text = "Steyn";
     worksheet.Range["A9"].Text = "Great Lakes Food Market";
     worksheet.Range["A10"].Text = "20 Whitehall Rd";
     worksheet.Range["A11"].Text = "North Muskegon,USA";
     worksheet.Range["A12"].Text = "+1 231-654-0000";
   
     //Create a Hyperlink for e-mail in the cell A13
     IHyperLink hyperlink = worksheet.HyperLinks.Add(worksheet.Range["A13"]);
     hyperlink.Type = ExcelHyperLinkType.Url;
     hyperlink.Address = "Steyn@greatlakes.com";
     hyperlink.ScreenTip = "Send Mail";
   
     //Enter details of products and prices
     worksheet.Range["A15"].Text = "  DESCRIPTION";
     worksheet.Range["C15"].Text = "QTY";
     worksheet.Range["D15"].Text = "UNIT PRICE";
     worksheet.Range["E15"].Text = "AMOUNT";
     worksheet.Range["A16"].Text = "Cabrales Cheese";
     worksheet.Range["A17"].Text = "Chocos";
     worksheet.Range["A18"].Text = "Pasta";
     worksheet.Range["A19"].Text = "Cereals";
     worksheet.Range["A20"].Text = "Ice Cream";
     worksheet.Range["C16"].Number = 3;
     worksheet.Range["C17"].Number = 2;
     worksheet.Range["C18"].Number = 1;
     worksheet.Range["C19"].Number = 4;
     worksheet.Range["C20"].Number = 3;
     worksheet.Range["D16"].Number = 21;
     worksheet.Range["D17"].Number = 54;
     worksheet.Range["D18"].Number = 10;
     worksheet.Range["D19"].Number = 20;
     worksheet.Range["D20"].Number = 30;
     worksheet.Range["D23"].Text = "Total";
   
     //Apply number format
     worksheet.Range["D16:E22"].NumberFormat = "$.00";
     worksheet.Range["E23"].NumberFormat = "$.00";
   
     //Merge column A and B from row 15 to 22
     worksheet.Range["A15:B15"].Merge();
     worksheet.Range["A16:B16"].Merge();
     worksheet.Range["A17:B17"].Merge();
     worksheet.Range["A18:B18"].Merge();
     worksheet.Range["A19:B19"].Merge();
     worksheet.Range["A20:B20"].Merge();
     worksheet.Range["A21:B21"].Merge();
     worksheet.Range["A22:B22"].Merge();
   
     //Apply incremental formula for column Amount by multiplying Qty and UnitPrice
     application.EnableIncrementalFormula = true;
     worksheet.Range["E16:E20"].Formula = "=C16*D16";
   
     //Formula for Sum the total
     worksheet.Range["E23"].Formula = "=SUM(E16:E22)";
   
     //Apply borders
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].Color = ExcelKnownColors.Grey_25_percent;
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].Color = ExcelKnownColors.Grey_25_percent;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].Color = ExcelKnownColors.Black;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].Color = ExcelKnownColors.Black;
   
     //Apply font setting for cells with product details
     worksheet.Range["A3:E23"].CellStyle.Font.FontName = "Arial";
     worksheet.Range["A3:E23"].CellStyle.Font.Size = 10;
     worksheet.Range["A15:E15"].CellStyle.Font.Color = ExcelKnownColors.White;
     worksheet.Range["A15:E15"].CellStyle.Font.Bold = true;
     worksheet.Range["D23:E23"].CellStyle.Font.Bold = true;
   
     //Apply cell color
     worksheet.Range["A15:E15"].CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189);
   
     //Apply alignment to cells with product details
     worksheet.Range["A15"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft;
     worksheet.Range["C15:C22"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
     worksheet.Range["D15:E15"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
   
     //Apply row height and column width to look good
     worksheet.Range["A1"].ColumnWidth = 36;
     worksheet.Range["B1"].ColumnWidth = 11;
     worksheet.Range["C1"].ColumnWidth = 8;
     worksheet.Range["D1:E1"].ColumnWidth = 18;
     worksheet.Range["A1"].RowHeight = 47;
     worksheet.Range["A2"].RowHeight = 15;
     worksheet.Range["A3:A4"].RowHeight = 15;
     worksheet.Range["A5"].RowHeight = 18;
     worksheet.Range["A6"].RowHeight = 29;
     worksheet.Range["A7"].RowHeight = 18;
     worksheet.Range["A8"].RowHeight = 15;
     worksheet.Range["A9:A14"].RowHeight = 15;
     worksheet.Range["A15:A23"].RowHeight = 18;
   
     // Save the Workbook
     StorageFile storageFile;
     if (!(Windows.Foundation.Metadata.ApiInformation.IsTypePresent("Windows.Phone.UI.Input.HardwareButtons")))
     {
       FileSavePicker savePicker = new FileSavePicker();
       savePicker.SuggestedStartLocation = PickerLocationId.Desktop;
       savePicker.SuggestedFileName = "Output";
       savePicker.FileTypeChoices.Add("Excel Files", new List<string>() { ".xlsx" });
       storageFile = await savePicker.PickSaveFileAsync();
     }
     else
     {
       StorageFolder local = Windows.Storage.ApplicationData.Current.LocalFolder;
       storageFile = await local.CreateFileAsync("Output.xlsx", CreationCollisionOption.ReplaceExisting);
     }
     //Saving the workbook
     await workbook.SaveAsAsync(storageFile);
   
     // Launch the saved file
     await Windows.System.Launcher.LaunchFileAsync(storageFile);
   }
Private Sub OnButtonClicked(ByVal sender As Object, ByVal args As EventArgs)
   'Create an instance of ExcelEngine
   Using excelEngine As ExcelEngine = New ExcelEngine()
     Dim application As IApplication = excelEngine.Excel
     application.DefaultVersion = ExcelVersion.Xlsx
   
     'Create a workbook
     Dim workbook As IWorkbook = application.Workbooks.Create(1)
     Dim worksheet As IWorksheet = workbook.Worksheets(0)
   
     'Adding a picture
     Dim executingAssembly As Assembly = GetType(MainPage).GetTypeInfo().Assembly
     Dim inputStream As Stream = executingAssembly.GetManifestResourceStream("GettingStarted_UWP.AdventureCycles-Logo.png")
     Dim shape As IPictureShape = worksheet.Pictures.AddPicture(1, 1, inputStream, 20, 20)
   
     'Disable gridlines in the worksheet
     worksheet.IsGridLinesVisible = False
   
     'Enter values to the cells from A3 to A5
     worksheet.Range("A3").Text = "46036 Michigan Ave"
     worksheet.Range("A4").Text = "Canton, USA"
     worksheet.Range("A5").Text = "Phone: +1 231-231-2310"
   
     'Make the text bold
     worksheet.Range("A3:A5").CellStyle.Font.Bold = True
   
     'Merge cells
     worksheet.Range("D1:E1").Merge()
   
     'Enter text to the cell D1 and apply formatting.
     worksheet.Range("D1").Text = "INVOICE"
     worksheet.Range("D1").CellStyle.Font.Bold = True
     worksheet.Range("D1").CellStyle.Font.RGBColor = ColorHelper.FromArgb(0, 42, 118, 189)
     worksheet.Range("D1").CellStyle.Font.Size = 35
   
     'Apply alignment in the cell D1
     worksheet.Range("D1").CellStyle.HorizontalAlignment = ExcelHAlign.HAlignRight
     worksheet.Range("D1").CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop
   
     'Enter values to the cells from D5 to E8
     worksheet.Range("D5").Text = "INVOICE#"
     worksheet.Range("E5").Text = "DATE"
     worksheet.Range("D6").Number = 1028
     worksheet.Range("E6").Value = "12/31/2018"
     worksheet.Range("D7").Text = "CUSTOMER ID"
     worksheet.Range("E7").Text = "TERMS"
     worksheet.Range("D8").Number = 564
     worksheet.Range("E8").Text = "Due Upon Receipt"
   
     'Apply RGB back color to the cells from D5 to E8
     worksheet.Range("D5:E5").CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189)
     worksheet.Range("D7:E7").CellStyle.Color = ColorHelper.FromArgb(0,42, 118, 189)
   
     'Apply known colors to the text in cells D5 to E8
     worksheet.Range("D5:E5").CellStyle.Font.Color = ExcelKnownColors.White
     worksheet.Range("D7:E7").CellStyle.Font.Color = ExcelKnownColors.White
   
     'Make the text as bold from D5 to E8
     worksheet.Range("D5:E8").CellStyle.Font.Bold = True
   
     'Apply alignment to the cells from D5 to E8
     worksheet.Range("D5:E8").CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter
     worksheet.Range("D5:E5").CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter
     worksheet.Range("D7:E7").CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter
     worksheet.Range("D6:E6").CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop
   
     'Enter value and applying formatting in the cell A7
     worksheet.Range("A7").Text = "  BILL TO"
     worksheet.Range("A7").CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189)
     worksheet.Range("A7").CellStyle.Font.Bold = True
     worksheet.Range("A7").CellStyle.Font.Color = ExcelKnownColors.White
   
     'Apply alignment
     worksheet.Range("A7").CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft
     worksheet.Range("A7").CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter
   
     'Enter values in the cells A8 to A12
     worksheet.Range("A8").Text = "Steyn"
     worksheet.Range("A9").Text = "Great Lakes Food Market"
     worksheet.Range("A10").Text = "20 Whitehall Rd"
     worksheet.Range("A11").Text = "North Muskegon,USA"
     worksheet.Range("A12").Text = "+1 231-654-0000"
   
     'Create a Hyperlink for e-mail in the cell A13
     Dim hyperlink As IHyperLink = worksheet.HyperLinks.Add(worksheet.Range("A13"))
     hyperlink.Type = ExcelHyperLinkType.Url
     hyperlink.Address = "Steyn@greatlakes.com"
     hyperlink.ScreenTip = "Send Mail"
   
     'Merge column A and B from row 15 to 22
     worksheet.Range("A15:B15").Merge()
     worksheet.Range("A16:B16").Merge()
     worksheet.Range("A17:B17").Merge()
     worksheet.Range("A18:B18").Merge()
     worksheet.Range("A19:B19").Merge()
     worksheet.Range("A20:B20").Merge()
     worksheet.Range("A21:B21").Merge()
     worksheet.Range("A22:B22").Merge()
   
     'Enter details of products and prices
     worksheet.Range("A15").Text = "  DESCRIPTION"
     worksheet.Range("C15").Text = "QTY"
     worksheet.Range("D15").Text = "UNIT PRICE"
     worksheet.Range("E15").Text = "AMOUNT"
     worksheet.Range("A16").Text = "Cabrales Cheese"
     worksheet.Range("A17").Text = "Chocos"
     worksheet.Range("A18").Text = "Pasta"
     worksheet.Range("A19").Text = "Cereals"
     worksheet.Range("A20").Text = "Ice Cream"
     worksheet.Range("C16").Number = 3
     worksheet.Range("C17").Number = 2
     worksheet.Range("C18").Number = 1
     worksheet.Range("C19").Number = 4
     worksheet.Range("C20").Number = 3
     worksheet.Range("D16").Number = 21
     worksheet.Range("D17").Number = 54
     worksheet.Range("D18").Number = 10
     worksheet.Range("D19").Number = 20
     worksheet.Range("D20").Number = 30
     worksheet.Range("D23").Text = "Total"
   
     'Apply number format
     worksheet.Range("D16:E22").NumberFormat = "$.00"
     worksheet.Range("E23").NumberFormat = "$.00"
   
     'Apply incremental formula for column Amount by multiplying Qty and UnitPrice
     application.EnableIncrementalFormula = True
     worksheet.Range("E16:E20").Formula = "=C16*D16"
   
     'Formula for Sum the total
     worksheet.Range("E23").Formula = "=SUM(E16:E22)"
   
     'Apply borders
     worksheet.Range("A16:E22").CellStyle.Borders(ExcelBordersIndex.EdgeTop).LineStyle = ExcelLineStyle.Thin
     worksheet.Range("A16:E22").CellStyle.Borders(ExcelBordersIndex.EdgeBottom).LineStyle = ExcelLineStyle.Thin
     worksheet.Range("A16:E22").CellStyle.Borders(ExcelBordersIndex.EdgeTop).Color = ExcelKnownColors.Grey_25_percent
     worksheet.Range("A16:E22").CellStyle.Borders(ExcelBordersIndex.EdgeBottom).Color = ExcelKnownColors.Grey_25_percent
     worksheet.Range("A23:E23").CellStyle.Borders(ExcelBordersIndex.EdgeTop).LineStyle = ExcelLineStyle.Thin
     worksheet.Range("A23:E23").CellStyle.Borders(ExcelBordersIndex.EdgeBottom).LineStyle = ExcelLineStyle.Thin
     worksheet.Range("A23:E23").CellStyle.Borders(ExcelBordersIndex.EdgeTop).Color = ExcelKnownColors.Black
     worksheet.Range("A23:E23").CellStyle.Borders(ExcelBordersIndex.EdgeBottom).Color = ExcelKnownColors.Black
   
     'Apply font setting for cells with product details
     worksheet.Range("A3:E23").CellStyle.Font.FontName = "Arial"
     worksheet.Range("A3:E23").CellStyle.Font.Size = 10
     worksheet.Range("A15:E15").CellStyle.Font.Color = ExcelKnownColors.White
     worksheet.Range("A15:E15").CellStyle.Font.Bold = True
     worksheet.Range("D23:E23").CellStyle.Font.Bold = True
   
     'Apply cell color
     worksheet.Range("A15:E15").CellStyle.Color = ColorHelper.FromArgb(0, 42, 118, 189)
   
     'Apply alignment to cells with product details
     worksheet.Range("A15").CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft
     worksheet.Range("C15:C22").CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter
     worksheet.Range("D15:E15").CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter
   
     'Apply row height and column width to look good
     worksheet.Range("A1").ColumnWidth = 36
     worksheet.Range("B1").ColumnWidth = 11
     worksheet.Range("C1").ColumnWidth = 8
     worksheet.Range("D1:E1").ColumnWidth = 18
     worksheet.Range("A1").RowHeight = 47
     worksheet.Range("A2").RowHeight = 15
     worksheet.Range("A3:A4").RowHeight = 15
     worksheet.Range("A5").RowHeight = 18
     worksheet.Range("A6").RowHeight = 29
     worksheet.Range("A7").RowHeight = 18
     worksheet.Range("A8").RowHeight = 15
     worksheet.Range("A9:A14").RowHeight = 15
     worksheet.Range("A15:A23").RowHeight = 18
   
     'Save the Workbook
     Dim storageFile As StorageFile
     If Not Windows.Foundation.Metadata.ApiInformation.IsTypePresent("Windows.Phone.UI.Input.HardwareButtons") Then
       Dim savePicker As FileSavePicker = New FileSavePicker
       savePicker.SuggestedStartLocation = PickerLocationId.Desktop
       savePicker.SuggestedFileName = "Output"
       savePicker.FileTypeChoices.Add("Excel Files", New List(Of String))
       storageFile = savePicker.PickSaveFileAsync
     Else
       Dim local As StorageFolder = Windows.Storage.ApplicationData.Current.LocalFolder
       storageFile = local.CreateFileAsync("Output.xlsx", CreationCollisionOption.ReplaceExisting)
     End If
   
     'Saving the workbook
     Function workbook_SaveAsAsync_((ByVal Unknown As storageFile) As await Implements workbook.SaveAsAsync.(Of
     End Function
   
     'Launch the saved file
     Function Windows_System_Launcher_LaunchFileAsync_((ByVal Unknown As storageFile) As await Implements Windows.System.Launcher.LaunchFileAsync.(Of
     End Function
   End Using

A complete working example of how to create an Excel file in UWP in C# is present on this GitHub page.

By executing the program, you will get the Excel file as below.
Output File
Output File

Read and Edit Excel file

The below code illustrates how to read and edit an Excel file in UWP.

//Create an instance of ExcelEngine
ExcelEngine excelEngine = new ExcelEngine();
IApplication application = excelEngine.Excel;

//Instantiates the File Picker. 
FileOpenPicker openPicker = new FileOpenPicker();
openPicker.SuggestedStartLocation = PickerLocationId.Desktop;
openPicker.FileTypeFilter.Add(".xlsx");
openPicker.FileTypeFilter.Add(".xls");
StorageFile openFile = await openPicker.PickSingleFileAsync();

//Opens the workbook. 
IWorkbook workbook = await application.Workbooks.OpenAsync(openFile);

//Access first worksheet from the workbook.
IWorksheet worksheet = workbook.Worksheets[0];

//Set Text in cell A3.
worksheet.Range["A3"].Text ="Hello World";

//Access a cell value from Excel
var value = worksheet.Range["A1"].Value;

//Sets workbook version.
workbook.Version = ExcelVersion.Xlsx;

//Initializes FileSavePicker.
FileSavePicker savePicker = new FileSavePicker();
savePicker.SuggestedStartLocation = PickerLocationId.Desktop;
savePicker.SuggestedFileName = "CreateSpreadsheet";
savePicker.FileTypeChoices.Add("Excel Files", new List<string>() { ".xlsx" });

//Creates a storage file from FileSavePicker.
StorageFile storageFile = await savePicker.PickSaveFileAsync();

//Saves changes to the specified storage file.
await workbook.SaveAsAsync(storageFile);

workbook.Close();
excelEngine.Dispose();
'Create an instance of ExcelEngine
Dim excelEngine As ExcelEngine = New ExcelEngine()
Dim application As IApplication = excelEngine.Excel

'Instantiates the File Save Picker.  
Dim openPicker As New FileOpenPicker()
openPicker.SuggestedStartLocation = PickerLocationId.Desktop 
openPicker.FileTypeFilter.Add(".xlsx") 
openPicker.FileTypeFilter.Add(".xls") 
Dim openFile As StorageFile = Await openPicker.PickSingleFileAsync()

'Opens the Workbook. 
Dim workbook As IWorkbook = Await application.Workbooks.OpenAsync(openFile)
Dim workbook.SaveAsAsyncCType(As await, openFile)

'Access first worksheet from the workbook.
Dim worksheet As IWorksheet = workbook.Worksheets(0)

'Set Text in cell A3.
worksheet.Range("A3").Text ="Hello World"

'Access a cell value from Excel
Dim value As var = worksheet.Range("A1").Value

'Sets workbook version.
workbook.Version = ExcelVersion.Xlsx

'Initializes FileSavePicker.
Dim savePicker As New FileSavePicker()
savePicker.SuggestedStartLocation = PickerLocationId.Desktop
savePicker.SuggestedFileName = "CreateSpreadsheet"
savePicker.FileTypeChoices.Add("Excel Files", New List(Of String)() From {".xlsx"})

'Creates a storage file from FileSavePicker.
Dim storageFile As StorageFile = Await savePicker.PickSaveFileAsync()

'Saves changes to the specified storage file.
Await workbook.SaveAsAsync(storageFile)

workbook.Close()
excelEngine.Dispose()

A complete working example of how to read and edit an Excel file in UWP in C# is present on this GitHub page.

Click here to explore the rich set of Syncfusion Excel library (XlsIO) features.

An online sample link to create an Excel document in ASP.NET Core.