Merge pull request #1340 from lagapollo/lagapollo-patch-1

Memory usage upgrade

SDWebImage/SDWebImageDecoder.m

@@ -13,6 +13,13 @@
 @implementation UIImage (ForceDecode)
 
 + (UIImage *)decodedImageWithImage:(UIImage *)image {
+    // while downloading huge amount of images
+    // autorelease the bitmap context
+    // and all vars to help system to free memory
+    // when there are memory warning.
+    // on iOS7, do not forget to call
+    // [[SDImageCache sharedImageCache] clearMemory];
+    @autoreleasepool{
         // do not decode animated images
         if (image.images) { return image; }
     
@@ -56,6 +63,7 @@
         CGImageRelease(imageRefWithAlpha);
         
         return imageWithAlpha;
+    }
 }
 
 @end