Load GIFs from disk in media view; don't cache GIF data in memory.

Signal/src/ViewControllers/MediaDetailViewController.m

@@ -35,8 +35,6 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic) UIView *replacingView;
 @property (nonatomic) UIButton *shareButton;
 
-@property (nonatomic) NSData *fileData;
-
 @property (nonatomic) TSAttachmentStream *attachmentStream;
 @property (nonatomic, nullable) ConversationViewItem *viewItem;
 @property (nonatomic, readonly) UIImage *image;
@@ -55,6 +53,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 @end
 
+#pragma mark -
+
 @implementation MediaDetailViewController
 
 - (void)dealloc
@@ -88,17 +88,6 @@ NS_ASSUME_NONNULL_BEGIN
     return self.attachmentStream.originalMediaURL;
 }
 
-- (NSData *)fileData
-{
-    if (!_fileData) {
-        NSURL *_Nullable url = self.attachmentUrl;
-        if (url) {
-            _fileData = [NSData dataWithContentsOfURL:url];
-        }
-    }
-    return _fileData;
-}
-
 - (BOOL)isAnimated
 {
     return self.attachmentStream.isAnimated;
@@ -184,7 +173,7 @@ NS_ASSUME_NONNULL_BEGIN
 
     if (self.isAnimated) {
         if (self.attachmentStream.isValidImage) {
-            YYImage *animatedGif = [YYImage imageWithData:self.fileData];
+            YYImage *animatedGif = [YYImage imageWithContentsOfFile:self.attachmentStream.originalFilePath];
             YYAnimatedImageView *animatedView = [YYAnimatedImageView new];
             animatedView.image = animatedGif;
             self.mediaView = animatedView;