Stop any video whenever leaving PageView

// FREEBIE

Signal/src/ViewControllers/MediaDetailViewController.m

@@ -79,6 +79,11 @@ NS_ASSUME_NONNULL_BEGIN
 
 @implementation MediaDetailViewController
 
+- (void)dealloc
+{
+    [self stopVideo];
+}
+
 - (instancetype)initWithGalleryItemBox:(GalleryItemBox *)galleryItemBox
                               viewItem:(ConversationViewItem *_Nullable)viewItem
 {

Signal/src/ViewControllers/MediaPageViewController.swift

@@ -8,11 +8,11 @@ import UIKit
 @objc
 public class GalleryItemBox: NSObject {
     public let value: MediaGalleryItem
-    
+
     init(_ value: MediaGalleryItem) {
         self.value = value
     }
-    
+
     public var attachmentStream: TSAttachmentStream {
         return value.attachmentStream
     }
@@ -190,6 +190,8 @@ class MediaPageViewController: UIPageViewController, UIPageViewControllerDataSou
     public func didPressAllMediaButton(sender: Any) {
         Logger.debug("\(logTag) in \(#function)")
 
+        currentViewController.stopVideo()
+
         guard let mediaGalleryDataSource = self.mediaGalleryDataSource else {
             owsFail("\(logTag) in \(#function) mediaGalleryDataSource was unexpectedly nil")
             return