Removed sync method `diskImageExistsWithKey:` from `SDImageCache`

@@ -227,15 +227,6 @@ typedef void(^SDWebImageCalculateSizeBlock)(NSUInteger fileCount, NSUInteger tot
 - (void)diskImageExistsWithKey:(nullable NSString *)key completion:(nullable SDWebImageCheckCacheCompletionBlock)completionBlock;
 
 /**
- *  Check if image exists in disk cache already (does not load the image)
- *
- *  @param key the key describing the url
- *
- *  @return YES if an image exists for the given key
- */
-- (BOOL)diskImageExistsWithKey:(nullable NSString *)key;
-
-/**
  *  Get the cache path for a certain key (needs the cache path root folder)
  *
  *  @param key  the key (can be obtained from url using cacheKeyForURL)

@@ -231,21 +231,6 @@ FOUNDATION_STATIC_INLINE NSUInteger SDCacheCostForImage(UIImage *image) {
     }
 }
 
-- (BOOL)diskImageExistsWithKey:(nullable NSString *)key {
-    BOOL exists = NO;
-    
-    // this is an exception to access the filemanager on another queue than ioQueue, but we are using the shared instance
-    // from apple docs on NSFileManager: The methods of the shared NSFileManager object can be called from multiple threads safely.
-    exists = [[NSFileManager defaultManager] fileExistsAtPath:[self defaultCachePathForKey:key]];
-
-    // fallback because of https://github.com/rs/SDWebImage/pull/976 that added the extension to the disk file name
-    // checking the key with and without the extension
-    if (!exists) {
-        exists = [[NSFileManager defaultManager] fileExistsAtPath:[self defaultCachePathForKey:key].stringByDeletingPathExtension];
-    }
-    
-    return exists;
-}
 
 - (void)diskImageExistsWithKey:(nullable NSString *)key completion:(nullable SDWebImageCheckCacheCompletionBlock)completionBlock {
     dispatch_async(_ioQueue, ^{