Add in voiceover accessibility (#32)

+semver: minor

Author: SearaChen

src/GMImagePicker/GMGridViewCell.cs

@@ -120,6 +120,8 @@ public void Initialize ()
 
 			// Note: the views above are created in case this is toggled per cell, on the fly, etc.!
 			ShouldShowSelection = true;
+			
+			ConfigureSelectButtonAccessibilityAttributes(_selectedButton, false);
 		}
 
 		// Required to resize the CAGradientLayer because it does not support auto resizing.
@@ -170,6 +172,13 @@ private string GetDurationWithFormat (double duration)
 			var minutes = (duration / 60) % 60;
 			return string.Format ("{0:00}:{1:00}", minutes, seconds);
 		}
+		
+		#region Voiceover Accessibility Configuration
+		private static void ConfigureSelectButtonAccessibilityAttributes(UIButton selectButton, bool isSelected)
+		{
+			selectButton.AccessibilityElementsHidden = true;
+		}
+		#endregion
 	}
 }
 

src/GMImagePicker/GMGridViewController.cs

@@ -507,7 +507,7 @@ public override void WillAnimateRotation (UIInterfaceOrientation toInterfaceOrie
 				_imageManager.RequestImageForAsset (typedCell.Asset,
 					AssetGridThumbnailSize,
 				    PHImageContentMode.AspectFill,
-                    options,
+                    options,
                     (image, info) => {
 						// Only update the thumbnail if the cell tag hasn't changed. Otherwise, the cell has been re-used.
 						if (cell.Tag == currentTag && typedCell.ImageView != null && image != null) {
@@ -563,7 +563,13 @@ public override UICollectionViewCell GetCell(UICollectionView collectionView, NS
 			{
 				cell.Selected = false;
 			}
-
+			
+            var resources = PHAssetResource.GetAssetResources(asset);
+            var name = resources != null && resources.Length > 0
+                ? resources[0].OriginalFilename
+                : string.Empty;
+            
+			ConfigureSelectCellAccessibilityAttributes(cell, cell.Selected , name);
 			return cell;
 		}
 
@@ -609,7 +615,8 @@ public override bool ShouldSelectItem(UICollectionView collectionView, NSIndexPa
 			var asset = (PHAsset)AssetsFetchResults[indexPath.Item];
 
 			var cell = (GMGridViewCell)collectionView.CellForItem(indexPath);
-
+			ConfigureSelectCellAccessibilityAttributes(cell, true, null);
+			
 			if (!cell.IsEnabled)
 			{
 				return false;
@@ -623,12 +630,34 @@ public override bool ShouldSelectItem(UICollectionView collectionView, NSIndexPa
 		public override void ItemDeselected(UICollectionView collectionView, NSIndexPath indexPath)
 		{
 			var asset = (PHAsset)AssetsFetchResults[indexPath.Item];
+			var cell = (GMGridViewCell)collectionView.CellForItem(indexPath);
 
 			_picker.DeselectAsset(asset);
 			_picker.NotifyAssetDeselected(asset);
+			ConfigureSelectCellAccessibilityAttributes(cell, false, null);
 		}
-	}
+		
+		#region Voiceover Accessibility Configuration
+		private static void ConfigureSelectCellAccessibilityAttributes(GMGridViewCell selectedCell, bool isSelected, string imageName)
+		{
+			selectedCell.AccessibilityTraits = UIAccessibilityTrait.Button;
+			selectedCell.IsAccessibilityElement = true;
+            if (imageName!=null)
+            {
+                selectedCell.AccessibilityLabel = imageName;
+            }
 
+			if (!isSelected)
+			{
+                selectedCell.AccessibilityHint = "picker.accessibility.check-to-select".Translate(defaultValue: "Check to select the image");
+			}
+			else
+			{
+                selectedCell.AccessibilityHint = "picker.accessibility.uncheck-to-deselect".Translate(defaultValue: "Uncheck to deselect the image");;
+			}
+		}
+		#endregion
+	}
 	#endregion
 }