Show an activity indicator until the preview has loaded.

Riot/Modules/Room/CellData/RoomBubbleCellData.h

@@ -82,10 +82,15 @@ typedef NS_ENUM(NSInteger, RoomBubbleCellDataTag)
 @property(nonatomic, readonly) CGFloat additionalContentHeight;
 
 /**
- A link if the textMessage contains one, otherwise nil.
+ The data necessary to show a URL preview.
  */
 @property (nonatomic) URLPreviewData *urlPreviewData;
 
+/**
+ Whether a URL preview should be displayed for this cell.
+ */
+@property (nonatomic) BOOL showURLPreview;
+
 /**
  MXKeyVerification object associated to key verification event when using key verification by direct message.
  */