feat(iOS): add fileopenpicker file limit

src/Uno.UWP/Storage/Pickers/FileOpenPicker.cs

@@ -13,6 +13,7 @@ public partial class FileOpenPicker : IFilePicker
 	{
 		private string _settingsIdentifier = string.Empty;
 		private string _commitButtonText = string.Empty;
+		private int _multipleFileLimit;
 
 		/// <summary>
 		/// Gets the collection of file types that the folder picker displays.
@@ -98,6 +99,22 @@ private void ValidateConfiguration()
 				throw new InvalidOperationException("You must provide at least a general file type filter ('*')");
 			}
 		}
+
+		internal void SetMultipleFileLimit(int limit)
+		{
+			_multipleFileLimit = limit;
+		}
 #endif
 	}
+
+	public static class FileOpenPickerExtensions
+	{
+		/// <summary>
+		/// Sets the file limit a user can select when picking multiple files.
+		/// </summary>
+		public static void SetLimit(this FileOpenPicker picker, int limit)
+		{
+			picker.SetMultipleFileLimit(limit);
+		}
+	}
 }

src/Uno.UWP/Storage/Pickers/FileOpenPicker.iOS.cs

@@ -51,7 +51,7 @@ private Task<IReadOnlyList<StorageFile>> PickMultipleFilesTaskAsync(Cancellation
 			return tcs.Task;
 		}
 
-		private UIViewController GetViewController(bool multiple, TaskCompletionSource<StorageFile?[]> completionSource)
+		private UIViewController GetViewController(bool multiple, int limit, TaskCompletionSource<StorageFile?[]> completionSource)
 		{
 			var iOS14AndAbove = UIDevice.CurrentDevice.CheckSystemVersion(14, 0);
 			switch (SuggestedStartLocation)
@@ -69,7 +69,7 @@ private UIViewController GetViewController(bool multiple, TaskCompletionSource<S
 					var imageConfiguration = new PHPickerConfiguration
 					{
 						Filter = PHPickerFilter.ImagesFilter,
-						SelectionLimit = 0
+						SelectionLimit = limit
 					};
 					return new PHPickerViewController(imageConfiguration)
 					{
@@ -79,7 +79,7 @@ private UIViewController GetViewController(bool multiple, TaskCompletionSource<S
 					var videoConfiguration = new PHPickerConfiguration
 					{
 						Filter = PHPickerFilter.VideosFilter,
-						SelectionLimit = 0
+						SelectionLimit = limit
 					};
 					return new PHPickerViewController(videoConfiguration)
 					{
@@ -90,7 +90,7 @@ private UIViewController GetViewController(bool multiple, TaskCompletionSource<S
 					var documentTypes = UTTypeMapper.GetDocumentTypes(FileTypeFilter);
 					return new UIDocumentPickerViewController(documentTypes, UIDocumentPickerMode.Open)
 					{
-						AllowsMultipleSelection = multiple,
+						AllowsMultipleSelection = multiple,						
 						ShouldShowFileExtensions = true,
 						Delegate = new FileOpenPickerDelegate(completionSource)
 					};
@@ -107,7 +107,7 @@ private async Task<FilePickerSelectedFilesArray> PickFilesAsync(bool multiple, C
 
 			var completionSource = new TaskCompletionSource<StorageFile?[]>();
 
-			using var viewController = this.GetViewController(multiple, completionSource);
+			using var viewController = this.GetViewController(multiple, _multipleFileLimit, completionSource);
 
 			viewController.OverrideUserInterfaceStyle = CoreApplication.RequestedTheme == SystemTheme.Light ?
 				UIUserInterfaceStyle.Light : UIUserInterfaceStyle.Dark;