{"user": {"first_name": "Blake", "last_name": "Watters", "email_address": "[email protected]"}}

RKObjectMapping *userMapping = [RKObjectMapping mappingForClass:[RKUser class]];
[userMapping addAttributeMappingsFromDictionary:@{ @"first_name": @"firstName", @"last_name": @"lastName", @"email_address", @"emailAddress" }];

[userMapping setSourceToDestinationKeyTransformationBlock:^NSString *(RKObjectMapping *mapping, NSString *sourceKey) {
    // Value transformer compliments of TransformerKit (See https://github.com/mattt/TransformerKit)
    return [[NSValueTransformer valueTransformerForName:TKLlamaCaseStringTransformerName] transformedValue:sourceKey];
}];

[userMapping addAttributeMappingsFromArray:@[ @"first_name", @"last_name", @"email_address" ]];

Tasks

Creating an Object Mapping

• + mappingForClass:

  Returns an object mapping for the specified class that is ready for configuration

• – initWithClass:

  Initializes the receiver with a given object class. This is the designated initializer.

• + requestMapping

  Returns an object mapping with an objectClass of NSMutableDictionary.

Accessing Property Mappings

•   propertyMappings

  The aggregate collection of attribute and relationship mappings within this object mapping.

  property
•   propertyMappingsBySourceKeyPath

  Returns the property mappings of the receiver in a dictionary, where the keys are the source key paths and the values are instances of RKAttributeMapping or RKRelationshipMapping.

  property
•   propertyMappingsByDestinationKeyPath

  Returns the property mappings of the receiver in a dictionary, where the keys are the destination key paths and the values are instances of RKAttributeMapping or RKRelationshipMapping.

  property
•   attributeMappings

  The collection of attribute mappings within this object mapping.

  property
•   relationshipMappings

  The collection of relationship mappings within this object mapping.

  property
• – mappingForSourceKeyPath:

  Returns the property mapping registered with the receiver with the given source key path.

• – mappingForDestinationKeyPath:

  Returns the property mapping registered with the receiver with the given destinationKeyPath key path.

• – addPropertyMapping:

  Adds a property mapping to the receiver.

• – addPropertyMappingsFromArray:

  Adds an array of RKAttributeMapping or RKRelationshipMapping objects to the receiver.

• – removePropertyMapping:

  Removes an RKAttributeMapping or RKRelationshipMapping from the receiver.

• – addAttributeMappingsFromDictionary:

  Adds attribute mappings from a given dictionary wherein the keys represent the source key path and the values represent the names of the target attributes on the destination object.

• – addAttributeMappingsFromArray:

  Adds attribute mappings to the receiver from a given array.

• – addRelationshipMappingWithSourceKeyPath:mapping:

  Adds a relationship mapping to the receiver with the given source key path and mapping.

Configuring Key Transformation

• + setDefaultSourceToDestinationKeyTransformationBlock:

  Sets an application-wide default transformation block to be used when attribute or relationship mappings are added to an object mapping by source key path.

• – setSourceToDestinationKeyTransformationBlock:

  Sets a block to executed to transform a source key into a destination key.

Mapping Nested Dictionaries

• – addAttributeMappingFromKeyOfRepresentationToAttribute:

  Adds an attribute mapping from a dynamic nesting key value to an attribute. The mapped attribute name can then be referenced within other attribute mappings to access the nested content.

• – addAttributeMappingToKeyOfRepresentationFromAttribute:

  Adds an attribute mapping to a dynamic nesting key from an attribute. The mapped attribute name can then be referenced wthin other attribute mappings to map content under the nesting key path.

Configuring Mapping Options

•   objectClass

  The target class that the receiver describes a mapping for.

  property
•   setDefaultValueForMissingAttributes

  When YES, any attributes that have mappings defined but are not present within the source object will be set to nil, clearing any existing value.

  property
•   setNilForMissingRelationships

  When YES, any relationships that have mappings defined but are not present within the source object will be set to nil, clearing any existing value.

  property
•   performKeyValueValidation

  When YES, key-value validation will be invoked at object mapping time.

  property
• – defaultValueForAttribute:

  Returns the default value to be assigned to the specified attribute when it is missing from a mappable payload.

Configuring Date Formatters

•   dateFormatters

  An array of NSFormatter objects to use when mapping string values into NSDate attributes on the target objectClass. Each date formatter will be invoked with the string value being mapped until one of the date formatters does not return nil.

  property
•   preferredDateFormatter

  The NSFormatter object for your application’s preferred date and time configuration. This date formatter will be used when generating string representations of NSDate attributes (i.e. during serialization to URL form encoded or JSON format).

  property
• – inverseMapping

  Generates an inverse mapping for the rules specified within this object mapping.

Obtaining Information About the Target Class

• – classForProperty:

  Returns the class of the attribute or relationship property of the target objectClass with the given name.

• – classForKeyPath:

  Returns the class of the attribute or relationship property of the target objectClass at the given key path.

DateAndTimeFormatting Methods

• + defaultDateFormatters

  Returns the collection of default date formatters that will be used for all object mappings that have not been configured specifically.

• + setDefaultDateFormatters:

  Sets the collection of default date formatters to the specified array. The array should contain configured instances of NSDateFormatter in the order in which you want them applied during object mapping operations.

• + addDefaultDateFormatter:

  Adds a date formatter instance to the default collection

• + addDefaultDateFormatterForString:inTimeZone:

  Convenience method for quickly constructing a date formatter and adding it to the collection of default date formatters. The locale is auto-configured to en_US_POSIX.

• + preferredDateFormatter

  Returns the preferred date formatter to use when generating NSString representations from NSDate attributes. This type of transformation occurs when RestKit is mapping local objects into JSON or form encoded serializations that do not have a native time construct.

• + setPreferredDateFormatter:

  Sets the preferred date formatter to use when generating NSString representations from NSDate attributes. This type of transformation occurs when RestKit is mapping local objects into JSON or form encoded serializations that do not have a native time construct.

 { "users":
     {
         "blake": { "id": 1234, "email": "[email protected]" },
         "rachit": { "id": 5678", "email": "[email protected]" }
     }
 }

 RKObjectMapping *mapping = [RKObjectMapping mappingForClass:[User class]];
 mapping.forceCollectionMapping = YES; // RestKit cannot infer this is a collection, so we force it
 [mapping addAttributeMappingFromKeyOfRepresentationToAttribute:@"firstName"];
 [mapping addAttributeMappingsFromDictionary:@{ @"(firstName).id": @"userID", @"(firstName).email": @"email" }];

RKUser *user = [RKUser new];
user.firstName = @"blake";
user.userID = @(1234);
user.email = @"[email protected]";

{ "blake": { "id": 1234, "email": "[email protected]" } }

 RKObjectMapping *mapping = [RKObjectMapping requestMapping];
 [mapping addAttributeMappingToKeyOfRepresentationFromAttribute:@"firstName"];
 [mapping addAttributeMappingsFromDictionary:@{ @"(firstName).userID": @"id", @"(firstName).email": @"email" }];