Addressed the review suggestion .

Author: deepika134

Annotations/PdfViewerAnnotations/PdfViewerAnnotations/MainPage.xaml.cs

@@ -10,7 +10,8 @@ public MainPage()
         {
             InitializeComponent();
             Stream? stream = typeof(MainPage).GetTypeInfo().Assembly.GetManifestResourceStream("PdfViewerAnnotations.Assets.Annotations.pdf");
-            PDFViewer.LoadDocument(stream);
+            if (stream != null)
+                PDFViewer.LoadDocument(stream);
         }
 
         private void AddHighlightAnnotation(object sender, EventArgs e)
@@ -44,36 +45,47 @@ private void RemoveAnnotation(object sender, EventArgs e)
             //Obtain the annotation collection.
             ReadOnlyObservableCollection<Annotation> annotations = PDFViewer.Annotations;
 
-            //Obtain the first annotation in the annotation collection.
-            Annotation firstAnnotation = annotations[3];
+            if (annotations != null && annotations.Count > 3 && annotations[3] != null)
+            {
 
-            //Remove the annotation using RemoveAnnotation method of `SfPdfViewer`.
-            PDFViewer.RemoveAnnotation(firstAnnotation);
+                //Obtain the annotation in the annotation collection.
+                Annotation annotation = annotations[3];
+
+                //Remove the annotation using RemoveAnnotation method of `SfPdfViewer`.
+                PDFViewer.RemoveAnnotation(annotation);
+            }
         }
 
         void EditAnnotation(object sender, EventArgs e)
         {
             // Obtain the annotation collection using
             ReadOnlyObservableCollection<Annotation> annotations = PDFViewer.Annotations;
 
-            // Obtain the first annotation in the annotation collection.
-            Annotation annotation = annotations[4];
+            if (annotations != null && annotations.Count > 4 && annotations[4] != null)
+            {
+
+                // Obtain the first annotation in the annotation collection.
+                Annotation annotation = annotations[4];
+
+                // Edit the annotation properties.
+                annotation.Color = Colors.Green; //Stroke color.
+                annotation.Opacity = 0.75f; // 75% Opacity
 
-            // Edit the annotation properties.
-            annotation.Color = Colors.Green; //Stroke color.
-            annotation.Opacity = 0.75f; // 75% Opacity
+            }
         }
 
         void PerformUndo(object sender, EventArgs e)
         {
             // Undo the last operation using the UndoCommand of `SfPdfViewer` instance.
-            PDFViewer.UndoCommand!.Execute(true);
+            if (PDFViewer.UndoCommand != null)
+                PDFViewer.UndoCommand.Execute(true);
         }
 
         void PerformRedo(object sender, EventArgs e)
         {
             // Redo the last operation using the RedoCommand of `SfPdfViewer` instance.
-            PDFViewer.RedoCommand!.Execute(true);
+            if (PDFViewer.RedoCommand != null)
+                PDFViewer.RedoCommand.Execute(true);
         }
     }
 

Annotations/PdfViewerAnnotations/README.md

@@ -0,0 +1,17 @@
+# Working with Annotations in .NET MAUI PDF Viewer
+
+This repository provides an example of how to add, edit, remove, and manage annotations in a PDF document using the **Syncfusion .NET MAUI PDF Viewer**, allowing users to interactively modify annotations within a PDF.
+
+## Process behind PDF annotation management
+
+The sample demonstrates how annotations can be programmatically created and modified directly within the loaded PDF document. Users can add highlight annotations to specific text areas, change annotation properties such as color and opacity, remove existing annotations, and use undo/redo actions to manage recent annotation changes.
+
+## Steps to use the sample
+
+1. Run the application to load a sample PDF document embedded in the project.
+2. Use the toolbar buttons to perform various annotation actions:
+   - **Add Annotation**: Inserts a new highlight annotation on a specified page location.
+   - **Remove Annotation**: Removes a specific annotation from the document.
+   - **Edit Annotation**: Changes the appearance of an existing annotation.
+   - **Undo Annotation**: Reverts the most recent annotation change.
+   - **Redo Annotation**: Re-applies the last undone annotation change.