From df751e737b0236c942a3f9e10f63c968b2d54fdd Mon Sep 17 00:00:00 2001
From: mythodeia <mythodeia@users.noreply.github.com>
Date: Wed, 15 Jul 2015 11:35:03 +0300
Subject: [PATCH] added option to disable memory cache

use this:
```shouldDisableMemoryCache``` to toggle memory cache
---
 SDWebImage/SDImageCache.h |  5 +++++
 SDWebImage/SDImageCache.m | 24 ++++++++++++++++--------
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/SDWebImage/SDImageCache.h b/SDWebImage/SDImageCache.h
index ca6033a5..2bbb902a 100644
--- a/SDWebImage/SDImageCache.h
+++ b/SDWebImage/SDImageCache.h
@@ -47,6 +47,11 @@ typedef void(^SDWebImageCalculateSizeBlock)(NSUInteger fileCount, NSUInteger tot
  */
 @property (assign, nonatomic) BOOL shouldDisableiCloud;
 
+/**
+ * use memory cache [defaults to YES]
+ */
+@property (assign, nonatomic) BOOL shouldCacheImagesInMemory;
+
 /**
  * The maximum "total cost" of the in-memory image cache. The cost function is the number of pixels held in memory.
  */
diff --git a/SDWebImage/SDImageCache.m b/SDWebImage/SDImageCache.m
index c197b5c3..f5ab18e9 100644
--- a/SDWebImage/SDImageCache.m
+++ b/SDWebImage/SDImageCache.m
@@ -116,6 +116,9 @@ FOUNDATION_STATIC_INLINE NSUInteger SDCacheCostForImage(UIImage *image) {
         // Set decompression to YES
         _shouldDecompressImages = YES;
 
+        // memory cache enabled
+        _shouldCacheImagesInMemory = YES;
+
         // Disable iCloud
         _shouldDisableiCloud = YES;
 
@@ -196,9 +199,11 @@ FOUNDATION_STATIC_INLINE NSUInteger SDCacheCostForImage(UIImage *image) {
     if (!image || !key) {
         return;
     }
-
-    NSUInteger cost = SDCacheCostForImage(image);
-    [self.memCache setObject:image forKey:key cost:cost];
+    // if memory cache is enabled
+    if (self.shouldCacheImagesInMemory) {
+        NSUInteger cost = SDCacheCostForImage(image);
+        [self.memCache setObject:image forKey:key cost:cost];
+    }
 
     if (toDisk) {
         dispatch_async(self.ioQueue, ^{
@@ -290,6 +295,7 @@ FOUNDATION_STATIC_INLINE NSUInteger SDCacheCostForImage(UIImage *image) {
 }
 
 - (UIImage *)imageFromDiskCacheForKey:(NSString *)key {
+
     // First check the in-memory cache...
     UIImage *image = [self imageFromMemoryCacheForKey:key];
     if (image) {
@@ -298,7 +304,7 @@ FOUNDATION_STATIC_INLINE NSUInteger SDCacheCostForImage(UIImage *image) {
 
     // Second check the disk cache...
     UIImage *diskImage = [self diskImageForKey:key];
-    if (diskImage) {
+    if (diskImage && self.shouldCacheImagesInMemory) {
         NSUInteger cost = SDCacheCostForImage(diskImage);
         [self.memCache setObject:diskImage forKey:key cost:cost];
     }
@@ -369,7 +375,7 @@ FOUNDATION_STATIC_INLINE NSUInteger SDCacheCostForImage(UIImage *image) {
 
         @autoreleasepool {
             UIImage *diskImage = [self diskImageForKey:key];
-            if (diskImage) {
+            if (diskImage && self.shouldCacheImagesInMemory) {
                 NSUInteger cost = SDCacheCostForImage(diskImage);
                 [self.memCache setObject:diskImage forKey:key cost:cost];
             }
@@ -400,9 +406,11 @@ FOUNDATION_STATIC_INLINE NSUInteger SDCacheCostForImage(UIImage *image) {
     if (key == nil) {
         return;
     }
-    
-    [self.memCache removeObjectForKey:key];
-    
+
+    if (self.shouldCacheImagesInMemory) {
+        [self.memCache removeObjectForKey:key];
+    }
+
     if (fromDisk) {
         dispatch_async(self.ioQueue, ^{
             [_fileManager removeItemAtPath:[self defaultCachePathForKey:key] error:nil];