Expose the memoryCache and diskCache object on `SDImageCache`, make it useful for user who have custom property beyond `SDImageCacheConfig`

SDWebImage/SDImageCache.h

@@ -11,6 +11,8 @@
 #import "SDWebImageDefine.h"
 #import "SDImageCacheConfig.h"
 #import "SDImageCacheDefine.h"
+#import "SDMemoryCache.h"
+#import "SDDiskCache.h"
 
 /// Image Cache Options
 typedef NS_OPTIONS(NSUInteger, SDImageCacheOptions) {
@@ -61,6 +63,21 @@ typedef NS_OPTIONS(NSUInteger, SDImageCacheOptions) {
  */
 @property (nonatomic, copy, nonnull, readonly) SDImageCacheConfig *config;
 
+/**
+ * The memory cache implementation object used for current image cache.
+ * By default we use `SDMemoryCache` class, you can also use this to call your own implementation class method.
+ * @note To customize this class, check `SDImageCacheConfig.memoryCacheClass` property.
+ */
+@property (nonatomic, strong, readonly, nonnull) id<SDMemoryCache> memoryCache;
+
+/**
+ * The disk cache implementation object used for current image cache.
+ * By default we use `SDMemoryCache` class, you can also use this to call your own implementation class method.
+ * @note To customize this class, check `SDImageCacheConfig.diskCacheClass` property.
+ * @warning When calling method about read/write in disk cache, be sure to either make your disk cache implementation IO-safe or using the same access queue to avoid issues.
+ */
+@property (nonatomic, strong, readonly, nonnull) id<SDDiskCache> diskCache;
+
 /**
  *  The disk cache's root path
  */

SDWebImage/SDImageCache.m

@@ -7,8 +7,6 @@
  */
 
 #import "SDImageCache.h"
-#import "SDMemoryCache.h"
-#import "SDDiskCache.h"
 #import "NSImage+Compatibility.h"
 #import "SDImageCodersManager.h"
 #import "SDImageTransformer.h"
@@ -20,8 +18,8 @@
 @interface SDImageCache ()
 
 #pragma mark - Properties
-@property (nonatomic, strong, nonnull) id<SDMemoryCache> memCache;
-@property (nonatomic, strong, nonnull) id<SDDiskCache> diskCache;
+@property (nonatomic, strong, readwrite, nonnull) id<SDMemoryCache> memoryCache;
+@property (nonatomic, strong, readwrite, nonnull) id<SDDiskCache> diskCache;
 @property (nonatomic, copy, readwrite, nonnull) SDImageCacheConfig *config;
 @property (nonatomic, copy, readwrite, nonnull) NSString *diskCachePath;
 @property (nonatomic, strong, nullable) dispatch_queue_t ioQueue;
@@ -71,7 +69,7 @@
         
         // Init the memory cache
         NSAssert([config.memoryCacheClass conformsToProtocol:@protocol(SDMemoryCache)], @"Custom memory cache class must conform to `SDMemoryCache` protocol");
-        _memCache = [[config.memoryCacheClass alloc] initWithConfig:_config];
+        _memoryCache = [[config.memoryCacheClass alloc] initWithConfig:_config];
         
         // Init the disk cache
         if (directory != nil) {
@@ -181,7 +179,7 @@
     // if memory cache is enabled
     if (toMemory && self.config.shouldCacheImagesInMemory) {
         NSUInteger cost = image.sd_memoryCost;
-        [self.memCache setObject:image forKey:key cost:cost];
+        [self.memoryCache setObject:image forKey:key cost:cost];
     }
     
     if (toDisk) {
@@ -219,7 +217,7 @@
         return;
     }
     NSUInteger cost = image.sd_memoryCost;
-    [self.memCache setObject:image forKey:key cost:cost];
+    [self.memoryCache setObject:image forKey:key cost:cost];
 }
 
 - (void)storeImageDataToDisk:(nullable NSData *)imageData
@@ -290,14 +288,14 @@
 }
 
 - (nullable UIImage *)imageFromMemoryCacheForKey:(nullable NSString *)key {
-    return [self.memCache objectForKey:key];
+    return [self.memoryCache objectForKey:key];
 }
 
 - (nullable UIImage *)imageFromDiskCacheForKey:(nullable NSString *)key {
     UIImage *diskImage = [self diskImageForKey:key];
     if (diskImage && self.config.shouldCacheImagesInMemory) {
         NSUInteger cost = diskImage.sd_memoryCost;
-        [self.memCache setObject:diskImage forKey:key cost:cost];
+        [self.memoryCache setObject:diskImage forKey:key cost:cost];
     }
 
     return diskImage;
@@ -423,7 +421,7 @@
                 diskImage = [self diskImageForKey:key data:diskData options:options context:context];
                 if (diskImage && self.config.shouldCacheImagesInMemory) {
                     NSUInteger cost = diskImage.sd_memoryCost;
-                    [self.memCache setObject:diskImage forKey:key cost:cost];
+                    [self.memoryCache setObject:diskImage forKey:key cost:cost];
                 }
             }
             
@@ -465,7 +463,7 @@
     }
 
     if (fromMemory && self.config.shouldCacheImagesInMemory) {
-        [self.memCache removeObjectForKey:key];
+        [self.memoryCache removeObjectForKey:key];
     }
 
     if (fromDisk) {
@@ -488,7 +486,7 @@
         return;
     }
     
-    [self.memCache removeObjectForKey:key];
+    [self.memoryCache removeObjectForKey:key];
 }
 
 - (void)removeImageFromDiskForKey:(NSString *)key {
@@ -512,7 +510,7 @@
 #pragma mark - Cache clean Ops
 
 - (void)clearMemory {
-    [self.memCache removeAllObjects];
+    [self.memoryCache removeAllObjects];
 }
 
 - (void)clearDiskOnCompletion:(nullable SDWebImageNoParamsBlock)completion {

Tests/Tests/SDImageCacheTests.m

@@ -14,13 +14,6 @@
 static NSString *kTestImageKeyJPEG = @"TestImageKey.jpg";
 static NSString *kTestImageKeyPNG = @"TestImageKey.png";
 
-@interface SDImageCache ()
-
-@property (nonatomic, strong, nonnull) id<SDMemoryCache> memCache;
-@property (nonatomic, strong, nonnull) id<SDDiskCache> diskCache;
-
-@end
-
 @interface SDImageCacheTests : SDTestCase <NSFileManagerDelegate>
 
 @end
@@ -380,7 +373,7 @@ static NSString *kTestImageKeyPNG = @"TestImageKey.png";
     config.memoryCacheClass = [SDWebImageTestMemoryCache class];
     NSString *nameSpace = @"SDWebImageTestMemoryCache";
     SDImageCache *cache = [[SDImageCache alloc] initWithNamespace:nameSpace diskCacheDirectory:nil config:config];
-    SDWebImageTestMemoryCache *memCache = cache.memCache;
+    SDWebImageTestMemoryCache *memCache = cache.memoryCache;
     expect([memCache isKindOfClass:[SDWebImageTestMemoryCache class]]).to.beTruthy();
 }