Update

FileReadAndWrite.csproj

@@ -57,6 +57,7 @@
 
 		<!-- Raw Assets (also remove the "Resources\Raw" prefix) -->
 		<MauiAsset Include="Resources\Raw\**" LogicalName="%(RecursiveDir)%(Filename)%(Extension)" />
+		<MauiAsset Include="Resources\Raw\data.txt" />
 	</ItemGroup>
 
 	<ItemGroup>

Service/FileService.cs

@@ -7,11 +7,18 @@ public class FileService
     public FileService()
     {
         // Plik, który będzie przechowywał zawartość naszej aplikacji
-        _filePath = Path.Combine(FileSystem.AppDataDirectory, "data.txt");
+        _filePath = Path.Combine(FileSystem.AppDataDirectory, "tekst.txt");
     }
 
-    public async Task SaveToFile(){
+    public async Task SaveToFile(string content){
+        await File.WriteAllTextAsync(_filePath, content);
+    }
 
+    public async Task<string> LoadFromFile(){
+        if (!File.Exists(_filePath))
+            return "Nie znaleziono pliku!";
+
+        return await File.ReadAllTextAsync(_filePath);
     }
     
     public async Task<string> LoadAsset(string asset){

View/AppDataFilePage.xaml

@@ -8,7 +8,10 @@
         <VerticalStackLayout
             Padding="30,0"
             Spacing="25">
-            
+            <Label Text="Zawartość, która jest zapisywana w plikach aplikacji:" />
+            <Entry Text="{Binding AppDataFileContent}" />
+            <Button Text="Załaduj dane" Command="{Binding LoadAppDataFileCmd}" />
+            <Button Text="Zapisz dane" Command="{Binding SaveAppDataFileCmd}" />
         </VerticalStackLayout>
     </ScrollView>
 

View/AppDataFilePage.xaml.cs

@@ -1,10 +1,14 @@
+using FileReadAndWrite.Service;
+using FileReadAndWrite.ViewModel;
+
 namespace FileReadAndWrite.View
 {
     public partial class AppDataFilePage : ContentPage
     {
-        public AppDataFilePage()
+        public AppDataFilePage(FileService fileService)
         {
             InitializeComponent();
+            BindingContext = new AppDataFilePageVM(fileService);
         }
     }
 }

View/RawFilePage.xaml.cs

@@ -1,31 +1,12 @@
-using System.ComponentModel;
-using System.Windows.Input;
 using FileReadAndWrite.Service;
+using FileReadAndWrite.ViewModel;
 
 namespace FileReadAndWrite.View;
 
 public partial class RawFilePage : ContentPage {
-    private readonly FileService _fileService;
-    private string _rawFileContent = "";
-    public string RawFileContent { 
-        get => _rawFileContent; 
-        set {
-            _rawFileContent = value;
-            OnPropertyChanged(nameof(RawFileContent));
-        } 
-    }
-
-    public ICommand LoadRawFileCmd { get; }
-
     public RawFilePage(FileService fileService) {
         InitializeComponent();
-        _fileService = fileService;
 
-        BindingContext = this;
-        LoadRawFileCmd = new Command(async () => await LoadRawFile());
-    }
-
-    public async Task LoadRawFile(){
-        RawFileContent = await _fileService.LoadAsset("data.txt");
+        BindingContext = new RawFilePageVM(fileService);
     }
 }

ViewModel/AppDataFilePageVM.cs

@@ -0,0 +1,43 @@
+using System.ComponentModel;
+using System.Windows.Input;
+using FileReadAndWrite.Model;
+using FileReadAndWrite.Service;
+using FileReadAndWrite.View;
+
+namespace FileReadAndWrite.ViewModel;
+
+public class AppDataFilePageVM : INotifyPropertyChanged {
+    private readonly FileService _fileService;
+
+    private string _appDataFileContent = "";
+    public string AppDataFileContent { 
+        get => _appDataFileContent; 
+        set {
+            _appDataFileContent = value;
+            OnPropertyChanged(nameof(AppDataFileContent));
+        } 
+    }
+
+    public ICommand LoadAppDataFileCmd { get; }
+    public ICommand SaveAppDataFileCmd { get; }
+
+    public AppDataFilePageVM(FileService fileService) {
+        _fileService = fileService;
+
+        LoadAppDataFileCmd = new Command(async () => await LoadAppDataFile());
+        SaveAppDataFileCmd = new Command(async () => await SaveAppDataFile());
+    }
+
+    public async Task LoadAppDataFile(){
+        AppDataFileContent = await _fileService.LoadFromFile();
+    }
+
+    public async Task SaveAppDataFile(){
+        await _fileService.SaveToFile(AppDataFileContent);
+    }
+
+    public event PropertyChangedEventHandler? PropertyChanged;
+    public void OnPropertyChanged(string propertyName) {
+        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+    }
+}

ViewModel/MainViewModel.cs

@@ -26,7 +26,7 @@ public class MainViewModel : INotifyPropertyChanged {
     }
 
     private async Task EnterAppDataFile(){
-        await _navigation.PushAsync(new AppDataFilePage());
+        await _navigation.PushAsync(new AppDataFilePage(_fileService));
     }
 
     public event PropertyChangedEventHandler? PropertyChanged;

ViewModel/RawFilePageVM.cs

@@ -0,0 +1,37 @@
+using System.ComponentModel;
+using System.Windows.Input;
+using FileReadAndWrite.Model;
+using FileReadAndWrite.Service;
+using FileReadAndWrite.View;
+
+namespace FileReadAndWrite.ViewModel;
+
+public class RawFilePageVM : INotifyPropertyChanged {
+    private readonly FileService _fileService;
+
+    private string _rawFileContent = "";
+    public string RawFileContent { 
+        get => _rawFileContent; 
+        set {
+            _rawFileContent = value;
+            OnPropertyChanged(nameof(RawFileContent));
+        } 
+    }
+
+    public ICommand LoadRawFileCmd { get; }
+
+    public RawFilePageVM(FileService fileService) {
+        _fileService = fileService;
+
+        LoadRawFileCmd = new Command(async () => await LoadRawFile());
+    }
+
+    public async Task LoadRawFile(){
+        RawFileContent = await _fileService.LoadAsset("data.txt");
+    }
+
+    public event PropertyChangedEventHandler? PropertyChanged;
+    public void OnPropertyChanged(string propertyName) {
+        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+    }
+}