From 0470f4b29fc664009a57d960df01ea0a25925e5b Mon Sep 17 00:00:00 2001
From: Mattt Thompson <m@mattt.me>
Date: Wed, 4 Apr 2012 16:31:52 -0700
Subject: [PATCH 1/8] [Issue #278] Adding thread safety to incrementing /
 decrementing and display of network activity indicator

---
 .../AFNetworkActivityIndicatorManager.m       | 24 +++++++++++++------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/AFNetworking/AFNetworkActivityIndicatorManager.m b/AFNetworking/AFNetworkActivityIndicatorManager.m
index a376d81..bdcb69a 100644
--- a/AFNetworking/AFNetworkActivityIndicatorManager.m
+++ b/AFNetworking/AFNetworkActivityIndicatorManager.m
@@ -30,6 +30,7 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
 @interface AFNetworkActivityIndicatorManager ()
 @property (readwrite, nonatomic, assign) NSInteger activityCount;
 @property (readwrite, nonatomic, retain) NSTimer *activityIndicatorVisibilityTimer;
+@property (readwrite, nonatomic, retain) NSRecursiveLock *lock;
 @property (readonly, getter = isNetworkActivityIndicatorVisible) BOOL networkActivityIndicatorVisible;
 
 - (void)updateNetworkActivityIndicatorVisibility;
@@ -38,6 +39,7 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
 @implementation AFNetworkActivityIndicatorManager
 @synthesize activityCount = _activityCount;
 @synthesize activityIndicatorVisibilityTimer = _activityIndicatorVisibilityTimer;
+@synthesize lock = _lock;
 @synthesize enabled = _enabled;
 @dynamic networkActivityIndicatorVisible;
 
@@ -56,6 +58,8 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
     if (!self) {
         return nil;
     }
+    
+    self.lock = [[[NSRecursiveLock alloc] init] autorelease];
 
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(incrementActivityCount) name:AFNetworkingOperationDidStartNotification object:nil];
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(decrementActivityCount) name:AFNetworkingOperationDidFinishNotification object:nil];
@@ -69,10 +73,13 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
     [_activityIndicatorVisibilityTimer invalidate];
     [_activityIndicatorVisibilityTimer release]; _activityIndicatorVisibilityTimer = nil;
     
+    [_lock release];
+    
     [super dealloc];
 }
 
 - (void)setActivityCount:(NSInteger)activityCount {
+    [self.lock lock];
     [self willChangeValueForKey:@"activityCount"];
     _activityCount = MAX(activityCount, 0);
     [self didChangeValueForKey:@"activityCount"];
@@ -87,6 +94,7 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
             [self updateNetworkActivityIndicatorVisibility];
         }
     }
+    [self.lock unlock];
 }
 
 - (BOOL)isNetworkActivityIndicatorVisible {
@@ -94,19 +102,21 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
 }
 
 - (void)updateNetworkActivityIndicatorVisibility {
-    [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:[self isNetworkActivityIndicatorVisible]];
+    dispatch_async(dispatch_get_main_queue(), ^{
+        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:[self isNetworkActivityIndicatorVisible]];
+    });
 }
 
 - (void)incrementActivityCount {
-    @synchronized(self) {
-        self.activityCount += 1;
-    }
+    [self.lock lock];
+    self.activityCount += 1;
+    [self.lock unlock];
 }
 
 - (void)decrementActivityCount {
-    @synchronized(self) {
-        self.activityCount -= 1;
-    }
+    [self.lock lock];
+    self.activityCount -= 1;
+    [self.lock unlock];
 }
 
 @end

From 88920034e2770ab86fa39f5cce1f334c2455a342 Mon Sep 17 00:00:00 2001
From: Peter Steinberger <me@petersteinberger.com>
Date: Wed, 4 Apr 2012 17:17:06 -0700
Subject: [PATCH 2/8] fixes a blocked reload button once we hit an error. Also
 shows an alert now.

---
 .../Classes/Controllers/PublicTimelineViewController.m      | 6 ++++--
 iOS Example/Classes/Models/Tweet.m                          | 6 ++++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/iOS Example/Classes/Controllers/PublicTimelineViewController.m b/iOS Example/Classes/Controllers/PublicTimelineViewController.m
index 8da1159..966b607 100644
--- a/iOS Example/Classes/Controllers/PublicTimelineViewController.m	
+++ b/iOS Example/Classes/Controllers/PublicTimelineViewController.m	
@@ -42,8 +42,10 @@
     self.navigationItem.rightBarButtonItem.enabled = NO;
     
     [Tweet publicTimelineTweetsWithBlock:^(NSArray *tweets) {
-        _tweets = tweets;
-        [self.tableView reloadData];
+        if (tweets) {
+            _tweets = tweets;
+            [self.tableView reloadData];
+        }
         
         [_activityIndicatorView stopAnimating];
         self.navigationItem.rightBarButtonItem.enabled = YES;
diff --git a/iOS Example/Classes/Models/Tweet.m b/iOS Example/Classes/Models/Tweet.m
index f53359d..d6bc1ec 100644
--- a/iOS Example/Classes/Models/Tweet.m	
+++ b/iOS Example/Classes/Models/Tweet.m	
@@ -65,6 +65,12 @@
         }
     } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
         NSLog(@"Error: %@", error);
+        
+        [[[UIAlertView alloc] initWithTitle:@"Error" message:[error localizedDescription] delegate:nil cancelButtonTitle:nil otherButtonTitles:@"Ok", nil] show];
+        
+        if (block) {
+            block(nil);
+        }
     }];
 }
 

From 069615a20d4c0de41cc3927d8cae5a16f0710c64 Mon Sep 17 00:00:00 2001
From: Peter Steinberger <me@petersteinberger.com>
Date: Thu, 5 Apr 2012 17:29:18 -0700
Subject: [PATCH 3/8] Use lightweight locking for activityCount

Also exposes isNetworkActivityIndicatorVisible which now is KVO observable.
---
 .../AFNetworkActivityIndicatorManager.h       | 12 +++---
 .../AFNetworkActivityIndicatorManager.m       | 41 ++++++++++---------
 2 files changed, 27 insertions(+), 26 deletions(-)

diff --git a/AFNetworking/AFNetworkActivityIndicatorManager.h b/AFNetworking/AFNetworkActivityIndicatorManager.h
index d15384a..2cee153 100644
--- a/AFNetworking/AFNetworkActivityIndicatorManager.h
+++ b/AFNetworking/AFNetworkActivityIndicatorManager.h
@@ -30,12 +30,7 @@
 /**
  `AFNetworkActivityIndicatorManager` manages the state of the network activity indicator in the status bar. When enabled, it will listen for notifications indicating that a network request operation has started or finished, and start or stop animating the indicator accordingly. The number of active requests is incremented and decremented much like a stack or a semaphore, and the activity indicator will animate so long as that number is greater than zero.
  */
-@interface AFNetworkActivityIndicatorManager : NSObject {
-@private
-	NSInteger _activityCount;
-    BOOL _enabled;
-    NSTimer *_activityIndicatorVisibilityTimer;
-}
+@interface AFNetworkActivityIndicatorManager : NSObject;
 
 /**
  A Boolean value indicating whether the manager is enabled. 
@@ -61,6 +56,11 @@
  */
 - (void)decrementActivityCount;
 
+/**
+ Returns the network indicator visibility. This is more excact than polling [UIApplication sharedApplication] isNetworkActivityIndicatorVisible] since we add a slight delay while updating the indicator to avoid flickering. You can observe this via KVO.
+ */
+- (BOOL)isNetworkActivityIndicatorVisible;
+
 @end
 
 #endif
diff --git a/AFNetworking/AFNetworkActivityIndicatorManager.m b/AFNetworking/AFNetworkActivityIndicatorManager.m
index bdcb69a..32dbbe0 100644
--- a/AFNetworking/AFNetworkActivityIndicatorManager.m
+++ b/AFNetworking/AFNetworkActivityIndicatorManager.m
@@ -23,6 +23,7 @@
 #import "AFNetworkActivityIndicatorManager.h"
 
 #import "AFHTTPRequestOperation.h"
+#import <libkern/OSAtomic.h>
 
 #if __IPHONE_OS_VERSION_MIN_REQUIRED
 static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
@@ -30,7 +31,6 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
 @interface AFNetworkActivityIndicatorManager ()
 @property (readwrite, nonatomic, assign) NSInteger activityCount;
 @property (readwrite, nonatomic, retain) NSTimer *activityIndicatorVisibilityTimer;
-@property (readwrite, nonatomic, retain) NSRecursiveLock *lock;
 @property (readonly, getter = isNetworkActivityIndicatorVisible) BOOL networkActivityIndicatorVisible;
 
 - (void)updateNetworkActivityIndicatorVisibility;
@@ -39,7 +39,6 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
 @implementation AFNetworkActivityIndicatorManager
 @synthesize activityCount = _activityCount;
 @synthesize activityIndicatorVisibilityTimer = _activityIndicatorVisibilityTimer;
-@synthesize lock = _lock;
 @synthesize enabled = _enabled;
 @dynamic networkActivityIndicatorVisible;
 
@@ -59,8 +58,6 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
         return nil;
     }
     
-    self.lock = [[[NSRecursiveLock alloc] init] autorelease];
-
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(incrementActivityCount) name:AFNetworkingOperationDidStartNotification object:nil];
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(decrementActivityCount) name:AFNetworkingOperationDidFinishNotification object:nil];
         
@@ -73,17 +70,10 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
     [_activityIndicatorVisibilityTimer invalidate];
     [_activityIndicatorVisibilityTimer release]; _activityIndicatorVisibilityTimer = nil;
     
-    [_lock release];
-    
     [super dealloc];
 }
 
-- (void)setActivityCount:(NSInteger)activityCount {
-    [self.lock lock];
-    [self willChangeValueForKey:@"activityCount"];
-    _activityCount = MAX(activityCount, 0);
-    [self didChangeValueForKey:@"activityCount"];
-
+- (void)updateNetworkActivityIndicatorVisibilityDelayed {
     if (self.enabled) {
         // Delay hiding of activity indicator for a short interval, to avoid flickering
         if (![self isNetworkActivityIndicatorVisible]) {
@@ -94,11 +84,10 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
             [self updateNetworkActivityIndicatorVisibility];
         }
     }
-    [self.lock unlock];
 }
 
 - (BOOL)isNetworkActivityIndicatorVisible {
-    return self.activityCount > 0;
+    return _activityCount > 0;
 }
 
 - (void)updateNetworkActivityIndicatorVisibility {
@@ -107,16 +96,28 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
     });
 }
 
+// not actually exposed, but will be used if someone tries to set activityCount via KVC.
+- (void)setActivityCount:(NSInteger)activityCount {
+    __sync_swap(&_activityCount, activityCount);
+    [self updateNetworkActivityIndicatorVisibilityDelayed];
+}
+
 - (void)incrementActivityCount {
-    [self.lock lock];
-    self.activityCount += 1;
-    [self.lock unlock];
+    [self willChangeValueForKey:@"activityCount"];
+    OSAtomicIncrement32((int32_t*)&_activityCount);
+    [self didChangeValueForKey:@"activityCount"];
+    [self updateNetworkActivityIndicatorVisibilityDelayed];
 }
 
 - (void)decrementActivityCount {
-    [self.lock lock];
-    self.activityCount -= 1;
-    [self.lock unlock];
+    [self willChangeValueForKey:@"activityCount"];
+    OSAtomicDecrement32((int32_t*)&_activityCount);
+    [self didChangeValueForKey:@"activityCount"];
+    [self updateNetworkActivityIndicatorVisibilityDelayed];
+}
+
++ (NSSet *)keyPathsForValuesAffectingIsNetworkActivityIndicatorVisible {
+    return [NSSet setWithObject:@"activityCount"];
 }
 
 @end

From e2751e6ffc0c88e2c3b58418d708daee60b3c135 Mon Sep 17 00:00:00 2001
From: Peter Steinberger <me@petersteinberger.com>
Date: Thu, 5 Apr 2012 17:49:08 -0700
Subject: [PATCH 4/8] protect decrementActivityCount against integer underflow.

---
 AFNetworking/AFNetworkActivityIndicatorManager.m | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/AFNetworking/AFNetworkActivityIndicatorManager.m b/AFNetworking/AFNetworkActivityIndicatorManager.m
index 32dbbe0..3e36ba6 100644
--- a/AFNetworking/AFNetworkActivityIndicatorManager.m
+++ b/AFNetworking/AFNetworkActivityIndicatorManager.m
@@ -111,7 +111,11 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
 
 - (void)decrementActivityCount {
     [self willChangeValueForKey:@"activityCount"];
-    OSAtomicDecrement32((int32_t*)&_activityCount);
+    bool success;
+    do {
+        int32_t orig = _activityCount;
+        success = OSAtomicCompareAndSwap32(orig, MIN(orig - 1, orig), &_activityCount);
+    } while(!success);
     [self didChangeValueForKey:@"activityCount"];
     [self updateNetworkActivityIndicatorVisibilityDelayed];
 }

From ed4c5587555ae730c17adeec11830f31f64e7fbd Mon Sep 17 00:00:00 2001
From: Peter Steinberger <me@petersteinberger.com>
Date: Fri, 6 Apr 2012 01:46:58 -0700
Subject: [PATCH 5/8] remote obsolete KVO change calls.

See http://petersteinberger.com/blog/2012/dont-call-willchangevalueforkey/.

I didn't remove the call in the AFNetworkActivityIndicatorManager, since I already removed this in my other pull request.
---
 AFNetworking/AFImageRequestOperation.m         | 2 --
 iOS Example/Classes/Views/TweetTableViewCell.m | 2 --
 2 files changed, 4 deletions(-)

diff --git a/AFNetworking/AFImageRequestOperation.m b/AFNetworking/AFImageRequestOperation.m
index 971cd14..d2943d2 100644
--- a/AFNetworking/AFImageRequestOperation.m
+++ b/AFNetworking/AFImageRequestOperation.m
@@ -170,9 +170,7 @@ static dispatch_queue_t image_request_operation_processing_queue() {
         return;
     }
     
-    [self willChangeValueForKey:@"imageScale"];
     _imageScale = imageScale;
-    [self didChangeValueForKey:@"imageScale"];
     
     self.responseImage = nil;
 }
diff --git a/iOS Example/Classes/Views/TweetTableViewCell.m b/iOS Example/Classes/Views/TweetTableViewCell.m
index 6fee1c0..f44c1f9 100644
--- a/iOS Example/Classes/Views/TweetTableViewCell.m	
+++ b/iOS Example/Classes/Views/TweetTableViewCell.m	
@@ -50,9 +50,7 @@
 }
 
 - (void)setTweet:(Tweet *)tweet {
-    [self willChangeValueForKey:@"tweet"];
     _tweet = tweet;
-    [self didChangeValueForKey:@"tweet"];
 
     self.textLabel.text = _tweet.user.username;
     self.detailTextLabel.text = _tweet.text;

From 6923e31db5b94052c4fcdd031ada4036ba758dcf Mon Sep 17 00:00:00 2001
From: Mattt Thompson <m@mattt.me>
Date: Sun, 8 Apr 2012 12:02:19 -0700
Subject: [PATCH 6/8] Minor code re-formatting and documentation changes

---
 AFNetworking/AFNetworkActivityIndicatorManager.h | 12 ++++++------
 AFNetworking/AFNetworkActivityIndicatorManager.m |  6 +++---
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/AFNetworking/AFNetworkActivityIndicatorManager.h b/AFNetworking/AFNetworkActivityIndicatorManager.h
index 2cee153..4a5640c 100644
--- a/AFNetworking/AFNetworkActivityIndicatorManager.h
+++ b/AFNetworking/AFNetworkActivityIndicatorManager.h
@@ -30,7 +30,7 @@
 /**
  `AFNetworkActivityIndicatorManager` manages the state of the network activity indicator in the status bar. When enabled, it will listen for notifications indicating that a network request operation has started or finished, and start or stop animating the indicator accordingly. The number of active requests is incremented and decremented much like a stack or a semaphore, and the activity indicator will animate so long as that number is greater than zero.
  */
-@interface AFNetworkActivityIndicatorManager : NSObject;
+@interface AFNetworkActivityIndicatorManager : NSObject
 
 /**
  A Boolean value indicating whether the manager is enabled. 
@@ -39,6 +39,11 @@
  */
 @property (nonatomic, assign, getter = isEnabled) BOOL enabled;
 
+/**
+ A Boolean value indicating whether the network activity indicator is currently displayed in the status bar.
+ */
+@property (readonly, nonatomic, assign) BOOL isNetworkActivityIndicatorVisible; 
+
 /**
  Returns the shared network activity indicator manager object for the system.
  
@@ -56,11 +61,6 @@
  */
 - (void)decrementActivityCount;
 
-/**
- Returns the network indicator visibility. This is more excact than polling [UIApplication sharedApplication] isNetworkActivityIndicatorVisible] since we add a slight delay while updating the indicator to avoid flickering. You can observe this via KVO.
- */
-- (BOOL)isNetworkActivityIndicatorVisible;
-
 @end
 
 #endif
diff --git a/AFNetworking/AFNetworkActivityIndicatorManager.m b/AFNetworking/AFNetworkActivityIndicatorManager.m
index 3e36ba6..01a6851 100644
--- a/AFNetworking/AFNetworkActivityIndicatorManager.m
+++ b/AFNetworking/AFNetworkActivityIndicatorManager.m
@@ -96,7 +96,7 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
     });
 }
 
-// not actually exposed, but will be used if someone tries to set activityCount via KVC.
+// Not exposed, but used if activityCount is set via KVC.
 - (void)setActivityCount:(NSInteger)activityCount {
     __sync_swap(&_activityCount, activityCount);
     [self updateNetworkActivityIndicatorVisibilityDelayed];
@@ -113,8 +113,8 @@ static NSTimeInterval const kAFNetworkActivityIndicatorInvisibilityDelay = 0.25;
     [self willChangeValueForKey:@"activityCount"];
     bool success;
     do {
-        int32_t orig = _activityCount;
-        success = OSAtomicCompareAndSwap32(orig, MIN(orig - 1, orig), &_activityCount);
+        int32_t currentCount = _activityCount;
+        success = OSAtomicCompareAndSwap32(currentCount, MIN(currentCount - 1, currentCount), &_activityCount);
     } while(!success);
     [self didChangeValueForKey:@"activityCount"];
     [self updateNetworkActivityIndicatorVisibilityDelayed];

From 14aea9ee58b70278ca2fc6ece17d0c4f4aa33929 Mon Sep 17 00:00:00 2001
From: Mattt Thompson <m@mattt.me>
Date: Sun, 8 Apr 2012 14:26:52 -0700
Subject: [PATCH 7/8] [Issue #268] Reverting to cacheing UIImages rather than
 NSPurgeableData-wrapped image data

---
 AFNetworking/UIImageView+AFNetworking.m | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/AFNetworking/UIImageView+AFNetworking.m b/AFNetworking/UIImageView+AFNetworking.m
index 9f9d190..5310e71 100644
--- a/AFNetworking/UIImageView+AFNetworking.m
+++ b/AFNetworking/UIImageView+AFNetworking.m
@@ -28,8 +28,8 @@
 
 @interface AFImageCache : NSCache
 - (UIImage *)cachedImageForRequest:(NSURLRequest *)request;
-- (void)cacheImageData:(NSData *)imageData
-            forRequest:(NSURLRequest *)request;
+- (void)cacheImage:(UIImage *)image
+        forRequest:(NSURLRequest *)request;
 @end
 
 #pragma mark -
@@ -121,7 +121,7 @@ static char kAFImageRequestOperationObjectKey;
                 success(operation.request, operation.response, responseObject);
             }
 
-            [[[self class] af_sharedImageCache] cacheImageData:operation.responseData forRequest:urlRequest];
+            [[[self class] af_sharedImageCache] cacheImage:responseObject forRequest:urlRequest];
             
             self.af_imageRequestOperation = nil;
         } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
@@ -162,18 +162,13 @@ static inline NSString * AFImageCacheKeyFromURLRequest(NSURLRequest *request) {
             break;
     }
     
-	UIImage *image = [UIImage imageWithData:[self objectForKey:AFImageCacheKeyFromURLRequest(request)]];
-	if (image) {
-		return [UIImage imageWithCGImage:[image CGImage] scale:[[UIScreen mainScreen] scale] orientation:image.imageOrientation];
-	}
-    
-    return image;
+	return [self objectForKey:AFImageCacheKeyFromURLRequest(request)];
 }
 
-- (void)cacheImageData:(NSData *)imageData
-            forRequest:(NSURLRequest *)request
+- (void)cacheImage:(UIImage *)image
+        forRequest:(NSURLRequest *)request
 {
-    [self setObject:[NSPurgeableData dataWithData:imageData] forKey:AFImageCacheKeyFromURLRequest(request)];
+    [self setObject:image forKey:AFImageCacheKeyFromURLRequest(request)];
 }
 
 @end

From 407374746c7106118f5a38136f5d700f216a32af Mon Sep 17 00:00:00 2001
From: Mattt Thompson <m@mattt.me>
Date: Sun, 8 Apr 2012 15:25:20 -0700
Subject: [PATCH 8/8] Removing unnecessary ivar declaration in headers

---
 AFNetworking/AFHTTPClient.h                   | 10 +---------
 AFNetworking/AFHTTPRequestOperation.h         |  9 +--------
 AFNetworking/AFImageRequestOperation.h        | 10 +---------
 AFNetworking/AFJSONRequestOperation.h         |  6 +-----
 AFNetworking/AFPropertyListRequestOperation.h |  8 +-------
 AFNetworking/AFURLConnectionOperation.h       | 19 +------------------
 AFNetworking/AFURLConnectionOperation.m       |  6 ++----
 AFNetworking/AFXMLRequestOperation.h          |  9 +--------
 8 files changed, 9 insertions(+), 68 deletions(-)

diff --git a/AFNetworking/AFHTTPClient.h b/AFNetworking/AFHTTPClient.h
index 687b9fd..e3d13b1 100644
--- a/AFNetworking/AFHTTPClient.h
+++ b/AFNetworking/AFHTTPClient.h
@@ -113,15 +113,7 @@ extern NSString * AFQueryStringFromParametersWithEncoding(NSDictionary *paramete
     [NSURL URLWithString:@"http://example2.com/" relativeToURL:baseURL];    // http://example2.com/
 
  */
-@interface AFHTTPClient : NSObject {
-@private
-    NSURL *_baseURL;
-    NSStringEncoding _stringEncoding;
-    AFHTTPClientParameterEncoding _parameterEncoding;
-    NSMutableArray *_registeredHTTPOperationClassNames;
-    NSMutableDictionary *_defaultHeaders;
-    NSOperationQueue *_operationQueue;
-}
+@interface AFHTTPClient : NSObject
 
 ///---------------------------------------
 /// @name Accessing HTTP Client Properties
diff --git a/AFNetworking/AFHTTPRequestOperation.h b/AFNetworking/AFHTTPRequestOperation.h
index 122099e..d906129 100644
--- a/AFNetworking/AFHTTPRequestOperation.h
+++ b/AFNetworking/AFHTTPRequestOperation.h
@@ -26,14 +26,7 @@
 /**
  `AFHTTPRequestOperation` is a subclass of `AFURLConnectionOperation` for requests using the HTTP or HTTPS protocols. It encapsulates the concept of acceptable status codes and content types, which determine the success or failure of a request.
  */
-@interface AFHTTPRequestOperation : AFURLConnectionOperation {
-@private
-    NSIndexSet *_acceptableStatusCodes;
-    NSSet *_acceptableContentTypes;
-    NSError *_HTTPError;
-    dispatch_queue_t _successCallbackQueue;
-    dispatch_queue_t _failureCallbackQueue;
-}
+@interface AFHTTPRequestOperation : AFURLConnectionOperation
 
 ///----------------------------------------------
 /// @name Getting HTTP URL Connection Information
diff --git a/AFNetworking/AFImageRequestOperation.h b/AFNetworking/AFImageRequestOperation.h
index 7456d5f..7a7f78a 100644
--- a/AFNetworking/AFImageRequestOperation.h
+++ b/AFNetworking/AFImageRequestOperation.h
@@ -49,15 +49,7 @@
  - `image/x-xbitmap`
  - `image/x-win-bitmap`
  */
-@interface AFImageRequestOperation : AFHTTPRequestOperation {
-@private
-#if __IPHONE_OS_VERSION_MIN_REQUIRED
-    UIImage *_responseImage;
-    CGFloat _imageScale;
-#elif __MAC_OS_X_VERSION_MIN_REQUIRED
-    NSImage *_responseImage;
-#endif
-}
+@interface AFImageRequestOperation : AFHTTPRequestOperation
 
 /**
  An image constructed from the response data. If an error occurs during the request, `nil` will be returned, and the `error` property will be set to the error.
diff --git a/AFNetworking/AFJSONRequestOperation.h b/AFNetworking/AFJSONRequestOperation.h
index 7c6a579..a1191f9 100644
--- a/AFNetworking/AFJSONRequestOperation.h
+++ b/AFNetworking/AFJSONRequestOperation.h
@@ -35,11 +35,7 @@
 
  @warning JSON parsing will automatically use JSONKit, SBJSON, YAJL, or NextiveJSON, if provided. Otherwise, the built-in `NSJSONSerialization` class is used, if available (iOS 5.0 and Mac OS 10.7). If the build target does not either support `NSJSONSerialization` or include a third-party JSON library, a runtime exception will be thrown when attempting to parse a JSON request. 
  */
-@interface AFJSONRequestOperation : AFHTTPRequestOperation {
-@private
-    id _responseJSON;
-    NSError *_JSONError;
-}
+@interface AFJSONRequestOperation : AFHTTPRequestOperation
 
 ///----------------------------
 /// @name Getting Response Data
diff --git a/AFNetworking/AFPropertyListRequestOperation.h b/AFNetworking/AFPropertyListRequestOperation.h
index 150041c..aa6e471 100644
--- a/AFNetworking/AFPropertyListRequestOperation.h
+++ b/AFNetworking/AFPropertyListRequestOperation.h
@@ -32,13 +32,7 @@
  
  - `application/x-plist`
  */
-@interface AFPropertyListRequestOperation : AFHTTPRequestOperation {
-@private
-    id _responsePropertyList;
-    NSPropertyListFormat _propertyListFormat;
-    NSPropertyListReadOptions _propertyListReadOptions;
-    NSError *_propertyListError;
-}
+@interface AFPropertyListRequestOperation : AFHTTPRequestOperation
 
 ///----------------------------
 /// @name Getting Response Data
diff --git a/AFNetworking/AFURLConnectionOperation.h b/AFNetworking/AFURLConnectionOperation.h
index 14d0226..bef89dc 100644
--- a/AFNetworking/AFURLConnectionOperation.h
+++ b/AFNetworking/AFURLConnectionOperation.h
@@ -75,24 +75,7 @@ extern NSString * const AFNetworkingOperationDidFinishNotification;
  
  @warning Attempting to load a `file://` URL in iOS 4 may result in an `NSInvalidArgumentException`, caused by the connection returning `NSURLResponse` rather than `NSHTTPURLResponse`, which is the behavior as of iOS 5.
  */
-@interface AFURLConnectionOperation : NSOperation {
-@private
-    unsigned short _state;
-    BOOL _cancelled;
-    NSRecursiveLock *_lock;
-    
-    NSSet *_runLoopModes;
-    
-    NSURLConnection *_connection;
-    NSURLRequest *_request;
-    NSHTTPURLResponse *_response;
-    NSError *_error;
-
-    NSData *_responseData;
-    NSInteger _totalBytesRead;
-    NSMutableData *_dataAccumulator;
-    NSOutputStream *_outputStream;
-}
+@interface AFURLConnectionOperation : NSOperation
 
 ///-------------------------------
 /// @name Accessing Run Loop Modes
diff --git a/AFNetworking/AFURLConnectionOperation.m b/AFNetworking/AFURLConnectionOperation.m
index 172595a..fe520e2 100644
--- a/AFNetworking/AFURLConnectionOperation.m
+++ b/AFNetworking/AFURLConnectionOperation.m
@@ -85,6 +85,7 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
 
 @interface AFURLConnectionOperation ()
 @property (readwrite, nonatomic, assign) AFOperationState state;
+@property (readwrite, nonatomic, assign, getter = isCancelled) BOOL cancelled;
 @property (readwrite, nonatomic, retain) NSRecursiveLock *lock;
 @property (readwrite, nonatomic, retain) NSURLConnection *connection;
 @property (readwrite, nonatomic, retain) NSURLRequest *request;
@@ -106,6 +107,7 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
 
 @implementation AFURLConnectionOperation
 @synthesize state = _state;
+@synthesize cancelled = _cancelled;
 @synthesize connection = _connection;
 @synthesize runLoopModes = _runLoopModes;
 @synthesize request = _request;
@@ -304,10 +306,6 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
     return self.state == AFHTTPOperationFinishedState;
 }
 
-- (BOOL)isCancelled {
-    return _cancelled;
-}
-
 - (BOOL)isConcurrent {
     return YES;
 }
diff --git a/AFNetworking/AFXMLRequestOperation.h b/AFNetworking/AFXMLRequestOperation.h
index 7fa919d..0beb677 100644
--- a/AFNetworking/AFXMLRequestOperation.h
+++ b/AFNetworking/AFXMLRequestOperation.h
@@ -39,14 +39,7 @@
  
  When `AFXMLRequestOperation` is registered with `AFHTTPClient`, the response object in the success callback of `HTTPRequestOperationWithRequest:success:failure:` will be an instance of `NSXMLParser`. On platforms that support `NSXMLDocument`, you have the option to ignore the response object, and simply use the `responseXMLDocument` property of the operation argument of the callback.
  */
-@interface AFXMLRequestOperation : AFHTTPRequestOperation {
-@private
-    NSXMLParser *_responseXMLParser;
-#if __MAC_OS_X_VERSION_MIN_REQUIRED
-    NSXMLDocument *_responseXMLDocument;
-#endif
-    NSError *_XMLError;
-}
+@interface AFXMLRequestOperation : AFHTTPRequestOperation
 
 ///----------------------------
 /// @name Getting Response Data