Fix memory cost override for SDAnimatedImage

SDWebImage/SDAnimatedImage.m

@@ -429,13 +429,9 @@ static NSArray *SDBundlePreferredScales() {
 
 @end
 
-@interface SDAnimatedImage (MemoryCacheCost)
-
-@end
-
 @implementation SDAnimatedImage (MemoryCacheCost)
 
-- (NSUInteger)sd_imageMemoryCost {
+- (NSUInteger)sd_memoryCost {
     NSNumber *value = objc_getAssociatedObject(self, @selector(sd_memoryCost));
     if (value != nil) {
         return value.unsignedIntegerValue;

SDWebImage/UIImage+MemoryCacheCost.h

@@ -16,8 +16,8 @@
  
  For `UIImage`, this method return the single frame bytes size when `image.images` is nil for static image. Retuen full frame bytes size when `image.images` is not nil for animated image.
  For `NSImage`, this method return the single frame bytes size because `NSImage` does not store all frames in memory.
- @note Note that because of the limitations of categories this property can get out of sync if you create another instance with CGImage or other methods.
- @note For custom animated class conforms to `SDAnimatedImage`, you can override this getter method in your subclass to return a more proper value instead, which representing the current frames' total bytes.
+ @note Note that because of the limitations of category this property can get out of sync if you create another instance with CGImage or other methods.
+ @note For custom animated class conforms to `SDAnimatedImage`, you can override this getter method in your subclass to return a more proper value instead, which representing the current frame's total bytes.
  */
 @property (assign, nonatomic) NSUInteger sd_memoryCost;