Some iOS/Android file picker fixes (#14677)

* Use NSSearchPathDomain.User when opening a known folder on iOS

* Use UIImagePickerController for WellKnownFolder.Pictures

* Improve how Android handles read permissions

src/Android/Avalonia.Android/Platform/Storage/AndroidStorageProvider.cs

@@ -55,12 +55,8 @@ internal class AndroidStorageProvider : IStorageProvider
             return null;
         }
 
-        var hasPerms = await _activity.CheckPermission(Manifest.Permission.ReadExternalStorage);
+        await EnsureUriReadPermission(androidUri);
-        if (!hasPerms)
+
-        {
-            throw new SecurityException("Application doesn't have ReadExternalStorage permission. Make sure android manifest has this permission defined and user allowed it.");
-        }
-        
         var javaFile = new JavaFile(androidUriPath);
         if (javaFile.Exists() && javaFile.IsFile)
         {
@@ -88,11 +84,7 @@ internal class AndroidStorageProvider : IStorageProvider
             return null;
         }
 
-        var hasPerms = await _activity.CheckPermission(Manifest.Permission.ReadExternalStorage);
+        await EnsureUriReadPermission(androidUri);
-        if (!hasPerms)
-        {
-            throw new SecurityException("Application doesn't have ReadExternalStorage permission. Make sure android manifest has this permission defined and user allowed it.");
-        }
 
         var javaFile = new JavaFile(androidUriPath);
         if (javaFile.Exists() && javaFile.IsDirectory)
@@ -283,4 +275,30 @@ internal class AndroidStorageProvider : IStorageProvider
 
         return null;
     }
+
+    private async Task EnsureUriReadPermission(AndroidUri androidUri)
+    {
+        bool hasPerms = false;
+        Exception? innerEx = null;
+        try
+        {
+            hasPerms = _activity.CheckUriPermission(androidUri,
+                global::Android.OS.Process.MyPid(),
+                global::Android.OS.Process.MyUid(),
+                ActivityFlags.GrantReadUriPermission)
+                == global::Android.Content.PM.Permission.Granted;
+
+            // TODO: call RequestPermission or add proper permissions API, something like in Browser File API.
+            hasPerms = hasPerms || await _activity.CheckPermission(Manifest.Permission.ReadExternalStorage);
+        }
+        catch (Exception ex)
+        {
+            innerEx = ex;
+        }
+
+        if (!hasPerms)
+        {
+            throw new InvalidOperationException("Application doesn't have READ_EXTERNAL_STORAGE permission. Make sure android manifest has this permission defined and user allowed it.", innerEx);
+        }
+    }
 }

src/iOS/Avalonia.iOS/Storage/IOSStorageItem.cs

@@ -179,6 +179,13 @@ internal sealed class IOSStorageFolder : IOSStorageItem, IStorageBookmarkFolder
     {
     }
 
+    public IOSStorageFolder(NSUrl url, WellKnownFolder wellKnownFolder) : base(url, null)
+    {
+        WellKnownFolder = wellKnownFolder;
+    }
+
+    public WellKnownFolder? WellKnownFolder { get; }
+
     public async IAsyncEnumerable<IStorageItem> GetItemsAsync()
     {
         try

src/iOS/Avalonia.iOS/Storage/IOSStorageProvider.cs

@@ -1,9 +1,7 @@
 using System;
 using System.Linq;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.Threading.Tasks;
-using Avalonia.Controls;
 using Avalonia.Logging;
 using Avalonia.Platform.Storage;
 using UIKit;
@@ -11,6 +9,7 @@ using Foundation;
 using UniformTypeIdentifiers;
 using UTTypeLegacy = MobileCoreServices.UTType;
 using UTType = UniformTypeIdentifiers.UTType;
+using System.Runtime.Versioning;
 
 namespace Avalonia.iOS.Storage;
 
@@ -28,51 +27,48 @@ internal class IOSStorageProvider : IStorageProvider
 
     public bool CanPickFolder => true;
 
-    public async Task<IReadOnlyList<IStorageFile>> OpenFilePickerAsync(FilePickerOpenOptions options)
+    public Task<IReadOnlyList<IStorageFile>> OpenFilePickerAsync(FilePickerOpenOptions options)
+    {
+        if (!options.AllowMultiple
+            && options.SuggestedStartLocation is IOSStorageFolder { WellKnownFolder: WellKnownFolder.Pictures })
+        {
+            return OpenImagePickerAsync(options);
+        }
+        else
+        {
+            return OpenDocumentsPickerAsync(options);
+        }
+    }
+
+    private async Task<IReadOnlyList<IStorageFile>> OpenImagePickerAsync(FilePickerOpenOptions options)
+    {
+#pragma warning disable CA1422 // Validate platform compatibility - we can't use PHImagePicker here.
+        using var imagePicker = new UIImagePickerController();
+        imagePicker.SourceType = UIImagePickerControllerSourceType.PhotoLibrary;
+        imagePicker.MediaTypes = new string[] { UTTypeLegacy.Image };
+        imagePicker.AllowsEditing = false;
+        imagePicker.Title = options.Title;
+#pragma warning restore CA1422 // Validate platform compatibility
+
+        var tcs = new TaskCompletionSource<NSUrl[]>();
+        imagePicker.Delegate = new ImageOpenPickerDelegate(urls => tcs.TrySetResult(urls));
+        var urls = await ShowPicker(imagePicker, tcs);
+
+        return urls.Select(u => new IOSStorageFile(u)).ToArray();
+    }
+
+    private async Task<IReadOnlyList<IStorageFile>> OpenDocumentsPickerAsync(FilePickerOpenOptions options)
     {
         UIDocumentPickerViewController documentPicker;
         if (OperatingSystem.IsIOSVersionAtLeast(14))
         {
-            var allowedUtils = options.FileTypeFilter?.SelectMany(f =>
+            var allowedTypes = FileTypesToUTType(options.FileTypeFilter);
-                {
+            documentPicker = new UIDocumentPickerViewController(allowedTypes!, false);
-                    // We check for OS version outside of the lambda, it's safe.
-#pragma warning disable CA1416
-                    if (f.TryGetExtensions() is { } extensions && extensions.Any())
-                    {
-                        return extensions.Select(UTType.CreateFromExtension);
-                    }
-                    if (f.AppleUniformTypeIdentifiers?.Any() == true)
-                    {
-                        return f.AppleUniformTypeIdentifiers.Select(UTType.CreateFromIdentifier);
-                    }
-                    if (f.MimeTypes?.Any() == true)
-                    {
-                        return f.MimeTypes.Select(UTType.CreateFromMimeType);
-                    }
-                    return Array.Empty<UTType>();
-#pragma warning restore CA1416
-                })
-                .Where(id => id is not null)
-                .ToArray() ?? new[]
-            {
-                UTTypes.Content,
-                UTTypes.Item,
-                UTTypes.Data
-            };
-            documentPicker = new UIDocumentPickerViewController(allowedUtils!, false);
         }
         else
         {
-            var allowedUtils = options.FileTypeFilter?.SelectMany(f => f.AppleUniformTypeIdentifiers ?? Array.Empty<string>())
+            var allowedTypes = FileTypesToUTTypeLegacy(options.FileTypeFilter);
-                .ToArray() ?? new[]
+            documentPicker = new UIDocumentPickerViewController(allowedTypes, UIDocumentPickerMode.Open);
-            {
-#pragma warning disable CA1422
-                UTTypeLegacy.Content,
-                UTTypeLegacy.Item,
-#pragma warning restore CA1422
-                "public.data"
-            };
-            documentPicker = new UIDocumentPickerViewController(allowedUtils, UIDocumentPickerMode.Open);
         }
 
         using (documentPicker)
@@ -87,7 +83,9 @@ internal class IOSStorageProvider : IStorageProvider
                 documentPicker.AllowsMultipleSelection = options.AllowMultiple;
             }
 
-            var urls = await ShowPicker(documentPicker);
+            documentPicker.Title = options.Title;
+
+            var urls = await ShowDocumentPicker(documentPicker);
             return urls.Select(u => new IOSStorageFile(u)).ToArray();
         }
     }
@@ -128,14 +126,19 @@ internal class IOSStorageProvider : IStorageProvider
             WellKnownFolder.Videos => NSSearchPathDirectory.MoviesDirectory,
             _ => throw new ArgumentOutOfRangeException(nameof(wellKnownFolder), wellKnownFolder, null)
         };
-        
+
-        var uri = NSFileManager.DefaultManager.GetUrl(directoryType, NSSearchPathDomain.Local, null, true, out var error);
+        var uri = NSFileManager.DefaultManager.GetUrl(directoryType, NSSearchPathDomain.User, null, true, out var error);
         if (error != null)
         {
             throw new NSErrorException(error);
         }
 
-        return Task.FromResult<IStorageFolder?>(new IOSStorageFolder(uri));
+        if (uri is null)
+        {
+            return Task.FromResult<IStorageFolder?>(null);
+        }
+
+        return Task.FromResult<IStorageFolder?>(new IOSStorageFolder(uri, wellKnownFolder));
     }
 
     public Task<IStorageFile?> SaveFilePickerAsync(FilePickerSaveOptions options)
@@ -162,7 +165,7 @@ internal class IOSStorageProvider : IStorageProvider
             documentPicker.AllowsMultipleSelection = options.AllowMultiple;
         }
         
-        var urls = await ShowPicker(documentPicker);
+        var urls = await ShowDocumentPicker(documentPicker);
         return urls.Select(u => new IOSStorageFolder(u)).ToArray();
     }
 
@@ -176,20 +179,24 @@ internal class IOSStorageProvider : IStorageProvider
         };
     }
 
-    private Task<NSUrl[]> ShowPicker(UIDocumentPickerViewController documentPicker)
+    private Task<NSUrl[]> ShowDocumentPicker(UIDocumentPickerViewController documentPicker)
     {
         var tcs = new TaskCompletionSource<NSUrl[]>();
         documentPicker.Delegate = new PickerDelegate(urls => tcs.TrySetResult(urls));
+        return ShowPicker(documentPicker, tcs);
+    }
 
-        if (documentPicker.PresentationController != null)
+    private Task<NSUrl[]> ShowPicker(UIViewController picker, TaskCompletionSource<NSUrl[]> tcs)
+    {
+        if (picker.PresentationController != null)
         {
-            documentPicker.PresentationController.Delegate =
+            picker.PresentationController.Delegate =
                 new UIPresentationControllerDelegate(() => tcs.TrySetResult(Array.Empty<NSUrl>()));
         }
 
         var controller = _view.Window?.RootViewController ?? throw new InvalidOperationException("RootViewController wasn't initialized");
-        controller.PresentViewController(documentPicker, true, null);
+        controller.PresentViewController(picker, true, null);
-        
+
         return tcs.Task;
     }
 
@@ -208,7 +215,73 @@ internal class IOSStorageProvider : IStorageProvider
         }
         return url;
     }
-        
+
+    private static string[] FileTypesToUTTypeLegacy(IReadOnlyList<FilePickerFileType>? filePickerFileTypes)
+    {
+        return filePickerFileTypes?
+            .SelectMany(f => f.AppleUniformTypeIdentifiers ?? Array.Empty<string>())
+            .ToArray() ?? new[]
+            {
+#pragma warning disable CA1422
+                UTTypeLegacy.Content,
+                UTTypeLegacy.Item,
+#pragma warning restore CA1422
+                "public.data"
+            };
+    }
+
+    [SupportedOSPlatform("ios14.0")]
+    private static UTType[] FileTypesToUTType(IReadOnlyList<FilePickerFileType>? filePickerFileTypes)
+    {
+        return filePickerFileTypes?.SelectMany(f =>
+        {
+            if (f.TryGetExtensions() is { } extensions && extensions.Any())
+            {
+                return extensions.Select(UTType.CreateFromExtension);
+            }
+            if (f.AppleUniformTypeIdentifiers?.Any() == true)
+            {
+                return f.AppleUniformTypeIdentifiers.Select(UTType.CreateFromIdentifier);
+            }
+            if (f.MimeTypes?.Any() == true)
+            {
+                return f.MimeTypes.Select(UTType.CreateFromMimeType);
+            }
+            return Array.Empty<UTType>();
+        })
+        .Where(id => id is not null)
+        .Cast<UTType>()
+        .ToArray() ?? new[]
+        {
+            UTTypes.Content,
+            UTTypes.Item,
+            UTTypes.Data
+        };
+    }
+
+    private class ImageOpenPickerDelegate : UIImagePickerControllerDelegate
+    {
+        private readonly Action<NSUrl[]>? _pickHandler;
+
+        internal ImageOpenPickerDelegate(Action<NSUrl[]> pickHandler)
+            => _pickHandler = pickHandler;
+
+        public override void Canceled(UIImagePickerController picker)
+            => _pickHandler?.Invoke(Array.Empty<NSUrl>());
+
+        public override void FinishedPickingMedia(UIImagePickerController picker, NSDictionary info)
+        {
+            if (info.ValueForKey(new NSString("UIImagePickerControllerImageURL")) is NSUrl nSUrl)
+            {
+                _pickHandler?.Invoke(new[] { nSUrl });
+            }
+            else
+            {
+                _pickHandler?.Invoke(Array.Empty<NSUrl>());
+            }
+        }
+    }
+
     private class PickerDelegate : UIDocumentPickerDelegate
     {
         private readonly Action<NSUrl[]>? _pickHandler;