Fix exception that occurs when attempting to build an RKMappingResult after an attempt has been made to map a non-nil, empty response object (such as {})

Code/ObjectMapping/RKMapperOperation.h

@@ -77,7 +77,7 @@
 
  @param object An `NSDictionary` or `NSArray` of `NSDictionary` object representations to be mapped into local domain objects.
  @param mappingsDictionary An `NSDictionary` wherein the keys are mappable key paths in `object` and the values are `RKMapping` objects specifying how the representations at its key path are to be mapped.
- @return The receiver, initialized with the given object
+ @return The receiver, initialized with the given object and and dictionary of key paths to mappings.
  */
 - (id)initWithObject:(id)object mappingsDictionary:(NSDictionary *)mappingsDictionary;
 
@@ -91,7 +91,7 @@
 @property (nonatomic, strong, readonly) NSError *error;
 
 /**
- The result of the mapping process.
+ The result of the mapping process. A `nil` value indicates that no mappable object representations were found and no mapping was performed.
  */
 @property (nonatomic, strong, readonly) RKMappingResult *mappingResult;
 
@@ -166,21 +166,21 @@
 ///-------------------------------
 
 /**
- Tells the delegate that the mapper has found a mappable object representation at a key path specified in the `mappingsDictionary` and is about to map it using a mapping.
+ Tells the delegate that the mapper has found one or more mappable object representations at a key path specified in the `mappingsDictionary`.
 
  @param mapper The mapper operation performing the mapping.
  @param dictionaryOrArrayOfDictionaries The `NSDictictionary` or `NSArray` of `NSDictionary` object representations that was found at the `keyPath`.
  @param keyPath The key path that the representation was read from in the `sourceObject`. If the `keyPath` was `[NSNull null]` in the `mappingsDictionary`, it will be given as `nil` to the delegate.
  */
-- (void)mapper:(RKMapperOperation *)mapper didFindRespresentation:(id)dictionaryOrArrayOfDictionaries atKeyPath:(NSString *)keyPath;
+- (void)mapper:(RKMapperOperation *)mapper didFindRepresentationOrArrayOfRepresentations:(id)dictionaryOrArrayOfDictionaries atKeyPath:(NSString *)keyPath;
 
 /**
- Tells the delegate that the mapper failed to find a mappable object at a key path specified in the `mappingsDictionary`.
+ Tells the delegate that the mapper failed to find any mappable object representations at a key path specified in the `mappingsDictionary`.
 
  @param mapper The mapper operation performing the mapping.
  @param keyPath The key path that was searched for a mappable object representation. 
  */
-- (void)mapper:(RKMapperOperation *)mapper didNotFindReprsentationAtKeyPath:(NSString *)keyPath;
+- (void)mapper:(RKMapperOperation *)mapper didNotFindRepresentationOrArrayOfRepresentationsAtKeyPath:(NSString *)keyPath;
 
 ///----------------------------------------------
 /// @name Tracking Child Mapping Operation Status

Code/ObjectMapping/RKMapperOperation.m

@@ -291,8 +291,8 @@ static NSString *RKDelegateKeyPathFromKeyPath(NSString *keyPath)
         if (mappableValue == nil || mappableValue == [NSNull null] || [self isNullCollection:mappableValue]) {
             RKLogDebug(@"Found unmappable value at keyPath: %@", keyPath);
 
-            if ([self.delegate respondsToSelector:@selector(mapper:didNotFindReprsentationAtKeyPath:)]) {
-                [self.delegate mapper:self didNotFindReprsentationAtKeyPath:RKDelegateKeyPathFromKeyPath(keyPath)];
+            if ([self.delegate respondsToSelector:@selector(mapper:didNotFindRepresentationOrArrayOfRepresentationsAtKeyPath:)]) {
+                [self.delegate mapper:self didNotFindRepresentationOrArrayOfRepresentationsAtKeyPath:keyPath];
             }
 
             continue;
@@ -301,8 +301,8 @@ static NSString *RKDelegateKeyPathFromKeyPath(NSString *keyPath)
         // Found something to map
         foundMappable = YES;
         RKMapping *mapping = [mappingsByKeyPath objectForKey:keyPath];
-        if ([self.delegate respondsToSelector:@selector(mapper:didFindRespresentation:atKeyPath:)]) {
-            [self.delegate mapper:self didFindRespresentation:mappableValue atKeyPath:RKDelegateKeyPathFromKeyPath(keyPath)];
+        if ([self.delegate respondsToSelector:@selector(mapper:didFindRepresentationOrArrayOfRepresentations:atKeyPath:)]) {
+            [self.delegate mapper:self didFindRepresentationOrArrayOfRepresentations:mappableValue atKeyPath:keyPath];
         }
 
         mappingResult = [self performMappingForObject:mappableValue atKeyPath:keyPath usingMapping:mapping];
@@ -353,7 +353,7 @@ static NSString *RKDelegateKeyPathFromKeyPath(NSString *keyPath)
 
     RKLogDebug(@"Finished performing object mapping. Results: %@", results);
 
-    self.mappingResult = [[RKMappingResult alloc] initWithDictionary:results];
+    if (results) self.mappingResult = [[RKMappingResult alloc] initWithDictionary:results];
 }
 
 @end

Code/ObjectMapping/RKMappingResult.m

@@ -46,7 +46,7 @@
 {
     // Flatten results down into a single array
     NSMutableArray *collection = [NSMutableArray array];
-    for (id object in [_keyPathToMappedObjects allValues]) {
+    for (id object in [self.keyPathToMappedObjects allValues]) {
         // We don't want to strip the keys off of a mapped dictionary result
         if (NO == [object isKindOfClass:[NSDictionary class]] && [object respondsToSelector:@selector(allObjects)]) {
             [collection addObjectsFromArray:[object allObjects]];

Tests/Logic/ObjectMapping/RKObjectMappingNextGenTest.m

@@ -650,7 +650,7 @@
 
     id userInfo = [RKTestFixture parsedObjectWithContentsOfFixture:@"user.json"];
     RKMapperOperation *mapper = [[RKMapperOperation alloc] initWithObject:userInfo mappingsDictionary:mappingsDictionary];
-    [[mockDelegate expect] mapper:mapper didFindRespresentation:OCMOCK_ANY atKeyPath:nil];
+    [[mockDelegate expect] mapper:mapper didFindRepresentationOrArrayOfRepresentations:OCMOCK_ANY atKeyPath:nil];
     mapper.delegate = mockDelegate;
     [mapper start];
     [mockDelegate verify];
@@ -665,7 +665,7 @@
     id userInfo = [RKTestFixture parsedObjectWithContentsOfFixture:@"user.json"];
     RKMapperOperation *mapper = [[RKMapperOperation alloc] initWithObject:userInfo mappingsDictionary:mappingsDictionary];
     id mockDelegate = [OCMockObject niceMockForProtocol:@protocol(RKMapperOperationDelegate)];
-    [[mockDelegate expect] mapper:mapper didNotFindReprsentationAtKeyPath:@"users"];
+    [[mockDelegate expect] mapper:mapper didNotFindRepresentationOrArrayOfRepresentationsAtKeyPath:@"users"];
     mapper.delegate = mockDelegate;
     [mapper start];
     [mockDelegate verify];