Allow user to provide reading options such as mapped file to improve performance in SDImageCache disk cache

SDWebImage/SDImageCache.m

@@ -311,14 +311,14 @@ FOUNDATION_STATIC_INLINE NSUInteger SDCacheCostForImage(UIImage *image) {
 
 - (nullable NSData *)diskImageDataBySearchingAllPathsForKey:(nullable NSString *)key {
     NSString *defaultPath = [self defaultCachePathForKey:key];
-    NSData *data = [NSData dataWithContentsOfFile:defaultPath];
+    NSData *data = [NSData dataWithContentsOfFile:defaultPath options:self.config.diskCacheReadingOptions error:nil];
     if (data) {
         return data;
     }
 
     // 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
-    data = [NSData dataWithContentsOfFile:defaultPath.stringByDeletingPathExtension];
+    data = [NSData dataWithContentsOfFile:defaultPath.stringByDeletingPathExtension options:self.config.diskCacheReadingOptions error:nil];
     if (data) {
         return data;
     }
@@ -326,14 +326,14 @@ FOUNDATION_STATIC_INLINE NSUInteger SDCacheCostForImage(UIImage *image) {
     NSArray<NSString *> *customPaths = [self.customPaths copy];
     for (NSString *path in customPaths) {
         NSString *filePath = [self cachePathForKey:key inPath:path];
-        NSData *imageData = [NSData dataWithContentsOfFile:filePath];
+        NSData *imageData = [NSData dataWithContentsOfFile:filePath options:self.config.diskCacheReadingOptions error:nil];
         if (imageData) {
             return imageData;
         }
 
         // 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
-        imageData = [NSData dataWithContentsOfFile:filePath.stringByDeletingPathExtension];
+        imageData = [NSData dataWithContentsOfFile:filePath.stringByDeletingPathExtension options:self.config.diskCacheReadingOptions error:nil];
         if (imageData) {
             return imageData;
         }

SDWebImage/SDImageCacheConfig.h

@@ -18,7 +18,7 @@
 @property (assign, nonatomic) BOOL shouldDecompressImages;
 
 /**
- *  disable iCloud backup [defaults to YES]
+ * disable iCloud backup [defaults to YES]
  */
 @property (assign, nonatomic) BOOL shouldDisableiCloud;
 
@@ -28,7 +28,13 @@
 @property (assign, nonatomic) BOOL shouldCacheImagesInMemory;
 
 /**
- * The maximum length of time to keep an image in the cache, in seconds
+ * The reading options while reading cache from disk.
+ * Defaults to 0. You can set this to mapped file to improve performance.
+ */
+@property (assign, nonatomic) NSDataReadingOptions diskCacheReadingOptions;
+
+/**
+ * The maximum length of time to keep an image in the cache, in seconds.
  */
 @property (assign, nonatomic) NSInteger maxCacheAge;