[IceCreamBuilder] Code refactoring

ios10/IceCreamBuilder/MessagesExtension/Model/IceCream.cs

@@ -149,15 +149,7 @@ public UIImage RenderParts ()
 		{
 			// Determine which parts to draw.
 			IceCreamPart[] allParts = { Topping, Scoops, Base };
-			var partImages = new List<UIImage> ();
-
-			foreach (var part in allParts) {
-				if (part != null && part.Image != null)
-					partImages.Add (part.StickerImage);
-			}
-
-			if (partImages == null)
-				return null;
+			var partImages = allParts.Where (p => p != null && p.Image != null).Select (p => p.StickerImage);
 
 			// Calculate the size of the composited ice cream parts image.
 			var outputImageSize = CGSize.Empty;

ios10/IceCreamBuilder/MessagesExtension/Model/IceCreamPart.cs

@@ -19,14 +19,11 @@ public class IceCreamPart : IQueryItemRepresentable {
 			}
 		}
 
+		UIImage stickerImage;
 		public UIImage StickerImage {
 			get {
-				var image = new UIImage ($"{RawValue}_sticker");
-
-				if (image == null)
-					throw new Exception ($"Unable to find sticker image");
-
-				return image;
+				stickerImage = stickerImage ?? new UIImage ($"{RawValue}_sticker");
+				return stickerImage;
 			}
 		}
 

ios10/IceCreamBuilder/MessagesExtension/Model/IceCreamStickerCache.cs

@@ -53,7 +53,7 @@ public void GetSticker (IceCream iceCream, Action<MSSticker> completion)
 				throw new Exception ("Stickers can only be created for completed ice creams");
 
 			// Determine the URL for the sticker.
-			var fileName = string.Format ($"{iceCream.Base.RawValue}{iceCream.Scoops.RawValue}{iceCream.Topping.RawValue}.png");
+			var fileName = $"{iceCream.Base.RawValue}{iceCream.Scoops.RawValue}{iceCream.Topping.RawValue}.png";
 			var url = Path.Combine (cacheURL, fileName);
 
 			// Check if the sticker already exists at the URL