The easiest way to marshall and unmarshall Dictionary representations such as JSON representation
Objective-C Swift Ruby

Build Status CocoaPod platform   CocoaPod version   Carthage compatible License MIT


An easy way to unmarshall a Dictionary of attributes (which came from JSON, XML or just a NSDictionary) into a Class and vice versa.


Developed by Lucas Medeiros and Denys Telezhkin



  • Suppose you have these classes:
typedef enum {
} Gender;

@interface Person : NSObject <EKMappingProtocol>

@property (nonatomic, copy)   NSString *name;
@property (nonatomic, copy)   NSString *email;
@property (nonatomic, assign) Gender gender;
@property (nonatomic, strong) Car *car;
@property (nonatomic, strong) NSArray *phones;
@property (nonatomic, strong) NSURL * socialURL;

@interface Car : NSObject <EKMappingProtocol>

@property (nonatomic, copy)   NSString *model;
@property (nonatomic, copy)   NSString *year;
@property (nonatomic, strong) NSDate *createdAt;


@interface Phone : NSObject <EKMappingProtocol>

@property (nonatomic, copy) NSString *DDI;
@property (nonatomic, copy) NSString *DDD;
@property (nonatomic, copy) NSString *number;


@interface Native : NSObject <EKMappingProtocol>

@property (nonatomic, readwrite) NSInteger integerProperty;
@property (nonatomic, readwrite) NSUInteger unsignedIntegerProperty;
@property (nonatomic, readwrite) CGFloat cgFloatProperty;
@property (nonatomic, readwrite) double doubleProperty;
@property (nonatomic, readwrite) BOOL boolProperty;

  • Mapping becomes as simple as implementing single method
@implementation Person

+(EKObjectMapping *)objectMapping
    return [EKObjectMapping mappingForClass:self withBlock:^(EKObjectMapping *mapping) {
        NSDictionary *genders = @{ @"male": @(GenderMale), @"female": @(GenderFemale) };
        [mapping mapPropertiesFromArray:@[@"name", @"email"]];
        [mapping mapKeyPath:@"gender" toProperty:@"gender" withValueBlock:^(NSString *key, id value) {
            return genders[value];
        } reverseBlock:^id(id value) {
           return [genders allKeysForObject:value].lastObject;
        [mapping mapKeyPath:@"socialURL" toProperty:@"socialURL"
             withValueBlock:[EKMappingBlocks urlMappingBlock]
               reverseBlock:[EKMappingBlocks urlReverseMappingBlock]];
        [mapping hasOne:[Car class] forKeyPath:@"car"];
        [mapping hasMany:[Phone class] forKeyPath:@"phones"];


@implementation Car

+(EKObjectMapping *)objectMapping
    return [EKObjectMapping mappingForClass:self withBlock:^(EKObjectMapping *mapping) {
        [mapping mapPropertiesFromArray:@[@"model", @"year"]];
        [mapping mapKeyPath:@"created_at" toProperty:@"createdAt" withDateFormatter:[NSDateFormatter ek_formatterForCurrentThread]];


@implementation Phone

+(EKObjectMapping *)objectMapping
    return [EKObjectMapping mappingForClass:self withBlock:^(EKObjectMapping *mapping) {
        [mapping mapPropertiesFromArray:@[@"number"]];
        [mapping mapPropertiesFromDictionary:@{
            @"ddi" : @"DDI",
            @"ddd" : @"DDD"


@implementation Native

+(EKObjectMapping *)objectMapping
    return [EKObjectMapping mappingForClass:self withBlock:^(EKObjectMapping *mapping) {
        [mapping mapPropertiesFromArray:@[
         @"integerProperty", @"unsignedIntegerProperty",
         @"cgFloatProperty", @"doubleProperty",

  • Converting a NSDictionary or NSArray to a object class or collection now becomes easy:
Person *person = [EKMapper objectFromExternalRepresentation:personRepresentation
                                                withMapping:[Person objectMapping]];

NSArray *carsArray = [EKMapper arrayOfObjectsFromExternalRepresentation:carsRepresentation
                                                            withMapping:[Car objectMapping]];
  • Converting an object/collection to NSDictionary/NSArray:
NSDictionary *representation = [EKSerializer serializeObject:car withMapping:[Car objectMapping]];
NSArray *collectionRepresentation = [EKSerializer serializeCollection:cars withMapping:[Car objectMapping]];
  • Filling an existent object:

Suppose you have something like this:

Person *person = [Person alloc] init]

To fill an already instantiated object you can do this:

[EKMapper fillObject:person fromExternalRepresentation:personRepresentation withMapping:[Person objectMapping]];


EasyMapping is partially compatible with Swift. Here's detailed look at EasyMapping usage in Swift and current limitations.

Convenience classes

EasyMapping provides two convenience base classes: EKObjectModel and EKManagedObjectModel, that implement EKMappingProtocol by default. If, for example, class Person would inherit from EKObjectModel, and implemented objectMapping method, all it would take to create Person instance from JSON representation would be:

NSDictionary * parsedPersonInfo = ...;
Person * person = [Person objectWithProperties:parsedPersonInfo];

And CoreData variant in case Person is EKManagedObjectModel subclass:

NSDictionary * parsedPersonInfo = ...;
Person * person = [Person objectWithProperties:parsedPersonInfo inContext:context];

Serializing to NSDictionary is even easier:

NSDictionary * info = [person serializedObject];


If you are using CoreData objects use EKManagedObjectMapping instead of EKObjectMapping. EasyMapping tries to speed up importing to database by scanning provided JSON and fetching all existing objects in batch. The more high level JSON will be provided, the more speed boost can be achieved.

Recursive mappings

Sometimes you can encounter situation, where your JSON will contain objects with links to objects of the same type. Good example would be comments, and replies to comments, that have tree-like structure. Starting with 0.7.0 recursive mappings are fully supported by EasyMapping.


Thanks to:

  • basitali who added the fillObject functionality on EKMapper!
  • Alejandro who added CoreData support!
  • Philip Vasilchenko who added the ability to serialization/deserialization of scalar types!
  • Dany L'Hébreux who added the NSSet support!
  • Jack who added mapFieldsFromMappingObject and mapFieldsFromArrayToPascalCase functionality
  • Yuri Kotov and Dmitriy which added a lot of performance improvements
  • Moya organization for awesome automated release process.


  • Xcode 6.3 and higher
  • iOS 5 and higher
  • Mac OS X 10.7 and higher
  • ARC


Using CocoaPods:

pod 'EasyMapping', '~> 0.20'

Using Carthage:

github "EasyMapping/EasyMapping"

Carthage uses dynamic frameworks, which require iOS 8.

Using Swift Package Manager:

Add the following as a dependency to your Package.swift:

.Package(url: "", majorVersion: 0, minorVersion: 2)

and then specify .Target(name: "EasyMapping") as a dependency of the Target in which you wish to use EasyMapping. Here's an example PackageDescription:

import PackageDescription

let package = Package(
  name: "MyApp",
  dependencies: [
    .Package(url: "", majorVersion: 0, minorVersion: 2)

The idea

The idea came from:

  • RestKit's mapping, its problem is that it doesn't transform custom values (such as a string value to an enum)
  • Mantle's mapping, but you don't need to inherit from any class