diff --git a/AFNetworking/AFHTTPRequestOperation.m b/AFNetworking/AFHTTPRequestOperation.m
index 23695cb..0247377 100644
--- a/AFNetworking/AFHTTPRequestOperation.m
+++ b/AFNetworking/AFHTTPRequestOperation.m
@@ -23,6 +23,8 @@
 #import "AFHTTPRequestOperation.h"
 #import "AFNetworkActivityIndicatorManager.h"
 
+#define AFHTTPMinContentLength 1024 * 1024 * 8
+
 typedef enum {
     AFHTTPOperationReadyState       = 1,
     AFHTTPOperationExecutingState   = 2,
@@ -107,6 +109,14 @@ static inline BOOL AFHTTPOperationStateTransitionIsValid(AFHTTPOperationState fr
 
 static NSThread *_networkRequestThread = nil;
 
++ (void)networkRequestThreadEntryPoint:(id)object {
+    do {
+        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+        [[NSRunLoop currentRunLoop] run];
+        [pool drain];
+    } while (YES);
+}
+
 + (NSThread *)networkRequestThread {
     static dispatch_once_t oncePredicate;
     
@@ -118,14 +128,6 @@ static NSThread *_networkRequestThread = nil;
     return _networkRequestThread;
 }
 
-+ (void)networkRequestThreadEntryPoint:(id)object {
-    do {
-        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
-        [[NSRunLoop currentRunLoop] run];
-        [pool drain];
-    } while (YES);
-}
-
 + (id)operationWithRequest:(NSURLRequest *)urlRequest 
                 completion:(void (^)(NSURLRequest *request, NSHTTPURLResponse *response, NSData *data, NSError *error))completion
 {
@@ -246,16 +248,6 @@ static NSThread *_networkRequestThread = nil;
     return YES;
 }
 
-- (void)start {
-    if (self.isFinished) {
-        return;
-    }
-    
-    self.state = AFHTTPOperationExecutingState;
-
-    [self performSelector:@selector(operationDidStart) onThread:[[self class] networkRequestThread] withObject:nil waitUntilDone:YES modes:[self.runLoopModes allObjects]];
-}
-
 - (void)operationDidStart {
     self.connection = [[[NSURLConnection alloc] initWithRequest:self.request delegate:self startImmediately:NO] autorelease];
     
@@ -269,6 +261,16 @@ static NSThread *_networkRequestThread = nil;
     
 }
 
+- (void)start {
+    if (self.isFinished) {
+        return;
+    }
+    
+    self.state = AFHTTPOperationExecutingState;
+
+    [self performSelector:@selector(operationDidStart) onThread:[[self class] networkRequestThread] withObject:nil waitUntilDone:YES modes:[self.runLoopModes allObjects]];
+}
+
 - (void)cancel {
     self.isCancelled = YES;
     
@@ -297,7 +299,10 @@ didReceiveResponse:(NSURLResponse *)response
     if (self.outputStream) {
         [self.outputStream open];
     } else {
-        NSUInteger contentLength = MIN(MAX(abs(response.expectedContentLength), 1024), 1024 * 1024 * 8);
+        NSUInteger contentLength = MAX(abs(response.expectedContentLength), 1024);
+        if (contentLength < AFHTTPMinContentLength) {
+            contentLength = AFHTTPMinContentLength;
+        }
         self.dataAccumulator = [NSMutableData dataWithCapacity:contentLength];
     }
 }
diff --git a/AFNetworking/UIImageView+AFNetworking.h b/AFNetworking/UIImageView+AFNetworking.h
index 0b79875..72a19ec 100644
--- a/AFNetworking/UIImageView+AFNetworking.h
+++ b/AFNetworking/UIImageView+AFNetworking.h
@@ -39,6 +39,6 @@
        placeholderImage:(UIImage *)placeholderImage 
               imageSize:(CGSize)imageSize 
                 options:(AFImageRequestOptions)options
-                  block:(void (^)(UIImage *image))block;
+                  block:(void (^)(UIImage *image, BOOL cacheUsed))block;
 
 @end
diff --git a/AFNetworking/UIImageView+AFNetworking.m b/AFNetworking/UIImageView+AFNetworking.m
index d1f5070..ebd483b 100644
--- a/AFNetworking/UIImageView+AFNetworking.m
+++ b/AFNetworking/UIImageView+AFNetworking.m
@@ -84,9 +84,12 @@ static NSString * const kUIImageViewImageRequestObjectKey = @"imageRequestOperat
        placeholderImage:(UIImage *)placeholderImage 
               imageSize:(CGSize)imageSize 
                 options:(AFImageRequestOptions)options
-                  block:(void (^)(UIImage *image))block
+                  block:(void (^)(UIImage *image, BOOL cacheUsed))block
 {
     if (!url) {
+        // stop loading image
+        [self.imageRequestOperation cancel];
+        self.imageRequestOperation = nil;
         return;
     }
     
@@ -99,20 +102,22 @@ static NSString * const kUIImageViewImageRequestObjectKey = @"imageRequestOperat
         self.image = cachedImage;
         
         if (block) {
-            block(cachedImage);
+            block(cachedImage, YES);
         }
     } else {
         self.image = placeholderImage;
         
         self.imageRequestOperation = [AFImageRequestOperation operationWithRequest:request imageSize:imageSize options:options success:^(UIImage *image) {
-            if ([[request URL] isEqual:[[self.imageRequestOperation request] URL]]) {
-                self.image = image;
-            } else {
-                self.image = placeholderImage;
-            }
-            
-            if (block) {
-                block(image);
+            if (self.imageRequestOperation && ![self.imageRequestOperation isCancelled]) {
+                if (block) {
+                    block(image, NO);
+                }
+
+                if ([[request URL] isEqual:[[self.imageRequestOperation request] URL]]) {
+                    self.image = image;
+                } else {
+                    self.image = placeholderImage;
+                }                
             }
         }];