Add imageFromMemoryCacheForKey: method to synchronously query the memory cache (fix #263)

README.md

@@ -145,8 +145,7 @@ SDImageCache *imageCache = [SDImageCache.alloc initWithNamespace:@"myNamespace"]
 ```
 
 By default SDImageCache will lookup the disk cache if an image can't be found in the memory cache.
-You can prevent this from happening by calling the alternative method imageFromKey:fromDisk: with a
-negative second argument.
+You can prevent this from happening by calling the alternative method `imageFromMemoryCacheForKey:`.
 
 To store an image into the cache, you use the storeImage:forKey: method:
 

SDWebImage/SDImageCache.h

@@ -87,6 +87,13 @@ typedef enum SDImageCacheType SDImageCacheType;
  */
 - (void)queryDiskCacheForKey:(NSString *)key done:(void (^)(UIImage *image, SDImageCacheType cacheType))doneBlock;
 
+/**
+ * Query the memory cache.
+ *
+ * @param key The unique key used to store the wanted image
+ */
+- (UIImage *)imageFromMemoryCacheForKey:(NSString *)key;
+
 /**
  * Remove the image from memory and disk cache synchronousely
  *

SDWebImage/SDImageCache.m

@@ -150,6 +150,11 @@ static const NSInteger kDefaultCacheMaxCacheAge = 60 * 60 * 24 * 7; // 1 week
     [self storeImage:image imageData:nil forKey:key toDisk:toDisk];
 }
 
+- (UIImage *)imageFromMemoryCacheForKey:(NSString *)key
+{
+    return [self.memCache objectForKey:key];
+}
+
 - (void)queryDiskCacheForKey:(NSString *)key done:(void (^)(UIImage *image, SDImageCacheType cacheType))doneBlock
 {
     if (!doneBlock) return;
@@ -161,7 +166,7 @@ static const NSInteger kDefaultCacheMaxCacheAge = 60 * 60 * 24 * 7; // 1 week
     }
 
     // First check the in-memory cache...
-    UIImage *image = [self.memCache objectForKey:key];
+    UIImage *image = [self imageFromMemoryCacheForKey:key];
     if (image)
     {
         doneBlock(image, SDImageCacheTypeMemory);