Adding the ability to render retina display images based on the file to which the url is pointing at

SDImageCache.m

@@ -169,13 +169,25 @@ static SDImageCache *instance;
         }
     }
 }
-
+- (UIImage *) imageForFile:(NSString*)fileKey {
+    NSString *file = [self cachePathForKey:fileKey];
+    NSData *imageData = [NSData dataWithContentsOfFile:file];
+    if (imageData) {
+        UIImage *image = [[[UIImage alloc] initWithData:imageData ] autorelease];
+        CGFloat scale = 1.0;
+        if ([fileKey hasSuffix:@"@2x.png"] || [fileKey hasSuffix:@"@2x.jpg"]) {
+            scale = 2.0;
+        }
+        return [[[UIImage alloc] initWithCGImage:image.CGImage scale:scale orientation:UIImageOrientationUp] autorelease];
+    }
+    return nil;
+}
 - (void)queryDiskCacheOperation:(NSDictionary *)arguments
 {
     NSString *key = [arguments objectForKey:@"key"];
     NSMutableDictionary *mutableArguments = [[arguments mutableCopy] autorelease];
     
-    UIImage *image = [[[UIImage alloc] initWithContentsOfFile:[self cachePathForKey:key]] autorelease];
+    UIImage *image = [self imageForFile:key];
     if (image)
     {
 #ifdef ENABLE_SDWEBIMAGE_DECODER
@@ -247,7 +259,7 @@ static SDImageCache *instance;
 
     if (!image && fromDisk)
     {
-        image = [[[UIImage alloc] initWithContentsOfFile:[self cachePathForKey:key]] autorelease];
+        UIImage *image = [self imageForFile:key];
         if (image)
         {
             [memCache setObject:image forKey:key];

SDWebImageDownloader.m

@@ -125,7 +125,14 @@ NSString *const SDWebImageDownloadStopNotification = @"SDWebImageDownloadStopNot
 
     if ([delegate respondsToSelector:@selector(imageDownloader:didFinishWithImage:)])
     {
-        UIImage *image = [[UIImage alloc] initWithData:imageData];
+        CGFloat scale = 1.0;
+        NSString *lastPathComponent = url.lastPathComponent;
+        if ([lastPathComponent hasSuffix:@"@2x.png"] || [lastPathComponent hasSuffix:@"@2x.jpg"]) {
+            scale = 2.0;
+        }
+        
+        UIImage *image = [[[UIImage alloc] initWithData:imageData ] autorelease];
+        image = [[UIImage alloc] initWithCGImage:image.CGImage scale:scale orientation:UIImageOrientationUp];
 
 #ifdef ENABLE_SDWEBIMAGE_DECODER
         [[SDWebImageDecoder sharedImageDecoder] decodeImage:image withDelegate:self userInfo:nil];