Add a way to check if data is in a format supported by a class implementing ASAnimatedImageProtocol

AsyncDisplayKit/ASNetworkImageNode.mm

@@ -469,9 +469,13 @@ static const CGSize kMinReleaseImageOnBackgroundSize = {20.0, 20.0};
 
             // If the file may be an animated gif and then created an animated image.
             id<ASAnimatedImageProtocol> animatedImage = nil;
-            if (_downloaderImplementsAnimatedImage && [_URL.pathExtension isEqualToString:@"gif"]) {
+            if (_downloaderImplementsAnimatedImage) {
               NSData *data = [NSData dataWithContentsOfURL:_URL];
               animatedImage = [_downloader animatedImageWithData:data];
+
+              if ([animatedImage respondsToSelector:@selector(isDataSupported:)] && [animatedImage isDataSupported:data] == NO) {
+                animatedImage = nil;
+              }
             }
 
             if (animatedImage != nil) {

AsyncDisplayKit/Details/ASImageProtocols.h

@@ -142,12 +142,21 @@ withDownloadIdentifier:(id)downloadIdentifier;
 
 @protocol ASAnimatedImageProtocol <NSObject>
 
+@optional
+
 /**
  @abstract Should be called when the objects cover image is ready.
  @param coverImageReadyCallback a block which receives the cover image.
  */
 @property (nonatomic, strong, readwrite) void (^coverImageReadyCallback)(UIImage *coverImage);
 
+/**
+ @abstract Returns whether the supplied data contains a supported animated image format.
+ @param data the data to check if contains a supported animated image.
+ */
+- (BOOL)isDataSupported:(NSData *)data;
+
+
 @required
 
 /**

AsyncDisplayKit/Details/ASPINRemoteImageDownloader.m

@@ -56,6 +56,11 @@
   return self.fileReady;
 }
 
+- (BOOL)isDataSupported:(NSData *)data
+{
+  return [data pin_isGIF];
+}
+
 @end
 #endif