I am trying to copy a library image to a persistent file path on an iOS device

Question

I can select an image from the device library and determine it's file path, but it appears that if I rebuild the app, in iOS, that path changes, so the image is effectively lost.
On Android, the path might be something like:

/DATA/USER/0/COM.MYWEB.APPNAME/FILES/2021013_145831.JPG

...and I can rebuild and deploy the app to my physical Android device and this path/filename is persistent.

On iOS, the path might be something like:

/var/mobile/Containers/Data/Application/A623D433-5D9A-43DA-B5D0-0EE477932BD4/Library/6B267A41-9865-43F2-A362-3EFA8EE5218A.jpeg-- 

The issue on iOS is that the path after /Application/ , and indeed after /Library/ , changes after every rebuild of the app so the path to the image is not persistent and is lost.

My hope is that I can rewrite the image to somewhere that will be persistent between builds.

This is my codebehind where I select a photo from the library and determine its path:

using HandsFreeNotes.Data;
using HandsFreeNotes.Model;
using HandsFreeNotes.ViewModel;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Essentials;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace HandsFreeNotes.View
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class OperatorInfoPage : ContentPage
    {

        OperatorModel _opm1;
        public OperatorModel opm1
        {
            get
            {
                return _opm1;
            }
            set
            {
                if (_opm1 != value)
                {
                    _opm1 = value;
                    OnPropertyChanged("opm1");
                }
            }
        }
        int SelectItemIndex;
        public EventHandler<OperatorModel> ReturnValue;

        public OperatorInfoPage(OperatorModel opm)
        {
            // add a bit of padding to cater to the "notch" on the iPhone.
            if (Device.RuntimePlatform == Device.iOS) { Padding = new Thickness(0, 40, 0, 0); }

            InitializeComponent();

            this.opm1 = opm;
            BindingContext = opm1;

            if (AvatarButton.Text == null)
            {
                AvatarButton.Text = "Click here to choose an avatar...";
            }
        }

        private async void BackButton_Clicked(object sender, EventArgs e)
        {
            await Navigation.PopModalAsync();
        }

        private async void OKButton_Clicked(object sender, EventArgs e)
        {

            var todoItem = (OperatorModel)BindingContext;
            PhotoPath = Preferences.Get("LastAvatar", null);

            if (PhotoPath != null)
            {
                todoItem.OperatorAvatar = PhotoPath;
                HFNDatabase database = await HFNDatabase.Instance;
                await database.SaveItemAsync(todoItem);
                Preferences.Set("LastAvatar", null);
            }

            EventHandler<OperatorModel> handler = ReturnValue;
            if (handler != null)
            {
                handler(this, todoItem);
            }
            await Navigation.PopModalAsync();
        }

        private async void CancelButton_Clicked(object sender, EventArgs e)
        {
            await Navigation.PopModalAsync();
        }

        private async void AvatarButton_Clicked(object sender, EventArgs e)
        {
            await TakePhotoAsync();
        }

        string PhotoPath;

        async Task TakePhotoAsync()
        {
            try
            {
                var photo = await MediaPicker.PickPhotoAsync();
                await LoadPhotoAsync(photo);
                var stream = photo.OpenReadAsync();
                // AvatarImage.Source = ImageSource.FromStream(() => stream);
                // await DisplayAlert("in", PhotoPath, "OK");
                AvatarButton.Text = PhotoPath;
                AvatarButton.TextColor = Color.DarkBlue;
                AvatarButton.FontSize = 14;
                AvatarImage.Source = PhotoPath;
                string NewOpName = NameEntry.Text;
                string NewOpAvatar = AvatarButton.Text;
                Preferences.Set("LastAvatar", PhotoPath);

            }

            catch (FeatureNotSupportedException fnsEx)
            {
                // Feature is not supported on the device
            }
            catch (PermissionException pEx)
            {
                // Permissions not granted
            }
            catch (Exception ex)
            {
                Console.WriteLine($"CapturePhotoAsync THREW: {ex.Message}");
            }
        }

        async Task LoadPhotoAsync(FileResult photo)
        {
            // canceled
            if (photo == null)
            {
                PhotoPath = null;
                return;
            }
            // save the file into local storage
            var newFile = Path.Combine(FileSystem.AppDataDirectory, photo.FileName);
            using (var stream = await photo.OpenReadAsync())
            using (var newStream = File.OpenWrite(newFile))
            await stream.CopyToAsync(newStream);
            PhotoPath = newFile;

            AvatarButton.Text = PhotoPath;
            AvatarButton.TextColor = Color.DarkBlue;
            AvatarButton.FontSize = 14;
            AvatarImage.Source = PhotoPath;
            string NewOpName = NameEntry.Text;
            string NewOpAvatar = AvatarButton.Text;
            Preferences.Set("LastAvatar", PhotoPath);
            // await DisplayAlert("Path to Avatar", PhotoPath, "Cancel");
            await Clipboard.SetTextAsync(PhotoPath);    // Xamarin Essentials clipboard grabber. GMB 1st time - 3/11/2021 
        }
    }
}

Answer 1

Hello,

Welcome to our Microsoft Q&A platform!

I have to say you shouldn't store raw file paths if you want to avoid this issue. A better practice would be to only store the relative part of the path and always attach it to the current "root" path. You could have a try with the following code:

Change the LoadPhotoAsync method by replacing PhotoPath .

  async Task LoadPhotoAsync(FileResult photo)  
  {  
      ..........  
      var newFile = Path.Combine(FileSystem.AppDataDirectory, photo.FileName);  
      using (var stream = await photo.OpenReadAsync())  
      using (var newStream = File.OpenWrite(newFile))  
          await stream.CopyToAsync(newStream);  
      PhotoPath = photo.FileName;  
      ............  
  }  

When you display the image, you need to combine the path.

AvatarImage.Source = Path.Combine(FileSystem.AppDataDirectory, PhotoPath);   

I also add a CombineOperatorAvatar property to OperatorModel, and change the ItemsSource of OperatorListView and databing to test the effect , it works.

Model

public string CombineOperatorAvatar { get; set; }  

SelectOperatorPage

 protected override async void OnAppearing()  
  {  
      base.OnAppearing();  
  
      HFNDatabase database = await HFNDatabase.Instance;  
      List< OperatorModel>dataList = await database.GetOperatorsAsync();  
      foreach (var OperatorModel in dataList)  
      {  
         OperatorModel.CombineOperatorAvatar = Path.Combine(FileSystem.AppDataDirectory, OperatorModel.OperatorAvatar);   
      }  
      OperatorListView.ItemsSource = dataList;  
  
  }  

XAML

   <Image  
         
       Source="{Binding CombineOperatorAvatar}"  
       Grid.Row="0"  
       Grid.Column="0"  
       Margin="5"  
       HeightRequest="100"  
       WidthRequest="100"/>  

Best Regards,
Wenyan Zhang

---

If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.