Migrated from Grand Central Dispatch queue for mapping into an NSOperationQueue to enable KVO

Code/ObjectMapping/RKObjectLoader.h

@@ -136,7 +136,8 @@ typedef void(^RKObjectLoaderDidLoadObjectsDictionaryBlock)(NSDictionary *diction
  * includes Core Data specific mapping logic.
  */
 @interface RKObjectLoader : RKRequest {
-    NSObject* _targetObject;
+    id _sourceObject;
+    id _targetObject;
 }
 
 /**
@@ -250,11 +251,11 @@ typedef void(^RKObjectLoaderDidLoadObjectsDictionaryBlock)(NSDictionary *diction
 @property (nonatomic, retain) NSObject *targetObject;
 
 /**
- The Grand Central Dispatch queue to perform our parsing and object mapping
+ The operation queue to perform our parsing and object mapping
  within. By default, object loaders will use the mappingQueue from the RKObjectManager
  that created the loader. You can override this on a per-loader basis as necessary.
  */
-@property (nonatomic, assign) dispatch_queue_t mappingQueue;
+@property (nonatomic, retain) NSOperationQueue *mappingQueue;
 
 ///////////////////////////////////////////////////////////////////////////////////////////
 

Code/ObjectMapping/RKObjectLoader.m

@@ -271,24 +271,22 @@
     return [self mapResponseWithMappingProvider:mappingProvider toObject:self.targetObject inContext:RKObjectMappingProviderContextObjectsByKeyPath error:error];
 }
 
-- (void)performMappingInDispatchQueue
+- (void)performMappingInOperationQueue
 {
     NSAssert(self.mappingQueue, @"mappingQueue cannot be nil");
-    dispatch_async(self.mappingQueue, ^{
-        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
-
-        RKLogDebug(@"Beginning object mapping activities within GCD queue labeled: %s", dispatch_queue_get_label(self.mappingQueue));
+    [self.mappingQueue addOperationWithBlock:^{
+        RKLogDebug(@"Beginning object mapping activities within GCD queue labeled: %@", self.mappingQueue.name);
         NSError *error = nil;
         _result = [[self performMapping:&error] retain];
         NSAssert(_result || error, @"Expected performMapping to return a mapping result or an error.");
         if (self.result) {
             [self processMappingResult:self.result];
         } else if (error) {
-            [self performSelectorOnMainThread:@selector(didFailLoadWithError:) withObject:error waitUntilDone:NO];
+            [[NSOperationQueue mainQueue] addOperationWithBlock:^{
+                [self didFailLoadWithError:error];
+            }];
         }
-
-        [pool drain];
-    });
+    }];
 }
 
 - (BOOL)canParseMIMEType:(NSString *)MIMEType
@@ -482,19 +480,6 @@
     }
 }
 
-- (void)setMappingQueue:(dispatch_queue_t)newMappingQueue
-{
-    if (_mappingQueue) {
-        dispatch_release(_mappingQueue);
-        _mappingQueue = nil;
-    }
-
-    if (newMappingQueue) {
-        dispatch_retain(newMappingQueue);
-        _mappingQueue = newMappingQueue;
-    }
-}
-
 // Proxy the delegate property back to our superclass implementation. The object loader should
 // really not be a subclass of RKRequest.
 - (void)setDelegate:(id<RKObjectLoaderDelegate>)delegate

Code/ObjectMapping/RKObjectManager.h

@@ -132,25 +132,26 @@ typedef enum {
 /** @name Object Mapping Dispatch Queue */
 
 /**
- Returns the global default Grand Central Dispatch queue used for object mapping
+ Returns the global default operation queue queue used for object mapping
  operations executed by RKObjectLoaders.
 
- All object loaders perform their loading within a Grand Central Dispatch
- queue. This provides control over the number of loaders that are performing
+ All object loaders perform their loading within an operation queue.
+ This provides control over the number of loaders that are performing
  expensive operations such as JSON parsing, object mapping, and accessing Core
  Data concurrently. The defaultMappingQueue is configured as the mappingQueue
  for all RKObjectManager's created by RestKit, but can be overridden on a per
  manager and per object loader basis.
 
- By default, the defaultMappingQueue is configured as serial GCD queue.
+ By default, the defaultMappingQueue is configured with a maximumConcurrentOperationCount
+ of 1.
  */
-+ (dispatch_queue_t)defaultMappingQueue;
++ (NSOperationQueue *)defaultMappingQueue;
 
 /**
- Sets a new global default Grand Central Dispatch queue for use in object mapping
+ Sets a new global default operation queue for use in object mapping
  operations executed by RKObjectLoaders.
  */
-+ (void)setDefaultMappingQueue:(dispatch_queue_t)defaultMappingQueue;
++ (void)setDefaultMappingQueue:(NSOperationQueue *)defaultMappingQueue;
 
 /// @name Initializing an Object Manager
 
@@ -233,10 +234,10 @@ typedef enum {
 @property (nonatomic, retain) RKManagedObjectStore *objectStore;
 
 /**
- The Grand Dispatch Queue to use when performing expensive object mapping operations
+ The operation queue to use when performing expensive object mapping operations
  within RKObjectLoader instances created through this object manager
  */
-@property (nonatomic, assign) dispatch_queue_t mappingQueue;
+@property (nonatomic, retain) NSOperationQueue *mappingQueue;
 
 /**
  The Default MIME Type to be used in object serialization.

Code/ObjectMapping/RKObjectManager.m

@@ -31,7 +31,7 @@ NSString * const RKObjectManagerDidBecomeOnlineNotification = @"RKDidEnterOnline
 // Shared Instances
 
 static RKObjectManager  *sharedManager = nil;
-static dispatch_queue_t defaultMappingQueue = nil;
+static NSOperationQueue *defaultMappingQueue = nil;
 
 ///////////////////////////////////
 
@@ -48,24 +48,26 @@ static dispatch_queue_t defaultMappingQueue = nil;
 @synthesize networkStatus = _networkStatus;
 @synthesize mappingQueue = _mappingQueue;
 
-+ (dispatch_queue_t)defaultMappingQueue
++ (NSOperationQueue *)defaultMappingQueue
 {
     if (! defaultMappingQueue) {
-        defaultMappingQueue = dispatch_queue_create("org.restkit.ObjectMapping", DISPATCH_QUEUE_SERIAL);
+        defaultMappingQueue = [NSOperationQueue new];
+        defaultMappingQueue.name = @"org.restkit.ObjectMapping";
+        defaultMappingQueue.maxConcurrentOperationCount = 1;
     }
 
     return defaultMappingQueue;
 }
 
-+ (void)setDefaultMappingQueue:(dispatch_queue_t)newDefaultMappingQueue
++ (void)setDefaultMappingQueue:(NSOperationQueue *)newDefaultMappingQueue
 {
     if (defaultMappingQueue) {
-        dispatch_release(defaultMappingQueue);
+        [defaultMappingQueue release];
         defaultMappingQueue = nil;
     }
 
     if (newDefaultMappingQueue) {
-        dispatch_retain(newDefaultMappingQueue);
+        [newDefaultMappingQueue retain];
         defaultMappingQueue = newDefaultMappingQueue;
     }
 }
@@ -426,19 +428,6 @@ static dispatch_queue_t defaultMappingQueue = nil;
     self.client.router = router;
 }
 
-- (void)setMappingQueue:(dispatch_queue_t)newMappingQueue
-{
-    if (_mappingQueue) {
-        dispatch_release(_mappingQueue);
-        _mappingQueue = nil;
-    }
-
-    if (newMappingQueue) {
-        dispatch_retain(newMappingQueue);
-        _mappingQueue = newMappingQueue;
-    }
-}
-
 #pragma mark - RKConfigrationDelegate
 
 - (void)configureRequest:(RKRequest *)request

Code/Testing/RKTestFactory.m

@@ -204,7 +204,7 @@ static RKTestFactory *sharedFactory = nil;
 
 + (void)setUp
 {
-    [RKObjectManager setDefaultMappingQueue:dispatch_queue_create("org.restkit.ObjectMapping", DISPATCH_QUEUE_SERIAL)];
+    [RKObjectManager setDefaultMappingQueue:nil];
     [RKObjectMapping setDefaultDateFormatters:nil];
 
     // Delete the store if it exists

Tests/Logic/ObjectMapping/RKObjectLoaderTest.m

@@ -650,7 +650,7 @@
     [userMapping mapAttributes:@"name", @"id", nil];
 
     // Suspend the Queue to block object mapping
-    dispatch_suspend(objectManager.mappingQueue);
+    [objectManager.mappingQueue setSuspended:YES];
 
     RKTestResponseLoader *responseLoader = [RKTestResponseLoader responseLoader];
     [objectManager.mappingProvider setObjectMapping:userMapping forResourcePathPattern:@"/humans/1"];