Latest 0.3.1
License Apache
Platforms ios 8.0, requires ARC
Dependencies AFNetworking, AtSugar, Avenue, AvenueFetcher, JSONModel, PromiseKit/CorePromise, UICKeyChainStore

CoreHound: Getting Started

What is CoreHound?

CoreHound is the iOS SDK for accessing The Entertainment Graph through MediaHound’s API. Search for media content across movies, books, games, TV, and more. Discover relationships across media via traits and contributors. CoreHound is a fast and easy SDK that lets you enhance your iOS apps with access to an entire world of entertainment content.

Install CoreHound

To get started with CoreHound, install it with CocoaPods. Add the following line to your Podfile:

pod 'CoreHound'

Run pod install, and you can now use CoreHound by importing it:

#import <CoreHound/MHApi.h>

Example Project

If you want to explore the example project, SearchLite, just run:

pod try CoreHound

The SearchLite project demonstrates many features like Application OAuth, Search, Images, and Contributor relationships.


Link Description
SDK Documentation Reference Documentation for CoreHound Homepage for MediaHound.
@MediaHound Follow MediaHound on Twitter.
Blog The MediaHound blog.
The Entertainment Graph Developer Portal
Changelog View changes introduced in each CoreHound version.

The world of media content

The Entertainment Graph contains many types of objects — movies, books, people, traits, etc.

The Entertainment Graph contains a series of objects representing media content, users, collections, etc and the connections between those objects. These objects and connections form a graph of media content. Social interactions live on top of that content graph.

Every object in The Entertainment Graph is uniquely identified by an identifier—- its mhid. For example, the movie Saving Private Ryan has an mhid of mhmovt8xqWDBFoCiL92HnfA4uYDV8HzPaig8ucgxJEsP.

Every object in The Entertainment Graph has a type—- Movie, Book, Contributor, etc. There is a well defined type hierarchy, so you can easily work with objects of varying types.

Saving Private Ryan is an MHMovie, and Catch 22 is an MHBook. Both MHMovie and MHBook inherit from MHMedia. This lets us work with entertainment across different content types easily. We can view the content as an MHMedia. When we need to specifically work with books, we can treat them as an MHBook.

All objects in The Entertainment Graph inherit from the MHObject class. This class provides the base functionality that all graph objects conform to. All objects have metadata represented as an MHMetadata:

Property Description
mhid The globally unique identifier of the object
altId A slug-like globally unique alternate identifier of the object
name A user-displayable name of the object
objectDescription A user-displayable description of the object
createdDate When the object was created in the graph

Some content types have more metadata properties. For example all MHMedia objects have an MHMediaMetadata which extends MHMetadata adding a releaseDate property.

Most MHObjects also have a primary image. The primary image is the main visual representation for the object. An MHImage provides image metadata including URLs to the image at varying resolutions.

MHObjects have relations to other MHObjects. For example, given an MHMovie, we can query for the people who have contributed to the movie (actors, director, composer, etc) like this:

[movie fetchContributors]; 

This gives you an array of MHContributors who are related to that movie.

The Entertainment Graph is highly connected. Here is a small example of the types of connections between content:

For a complete list of types visit Graph Objects.

CoreHound is highly asynchronous

Almost all interaction you have with the CoreHound SDK is through asynchronous APIs. CoreHound uses promises as its asynchronous pattern. As a simple example, to find the release date of The Usual Suspects, you would write:

NSString* theUsualSuspectsMhid = @"mhmovI8Y9tWpUFibqYGZYddt1I5q3znlRAuSQ2a6N437";
[MHObject fetchByMhid:theUsualSuspectsMhid].then(^(MHObject* result) {
    NSDate* releaseDate = result.metadata.releaseDate;
    NSLog(@"The Usual Suspects (%@)", releaseDate);

The PromiseKit docs are a great way to learn more about how to interact with promises.

Objects are progressively loaded

Since The Entertainment Graph contains so much information about each object and all of its relationships, you must always explicitly fetch the data you want.

If you want to load the primary image for a movie, you must do this:

[movie fetchPrimaryImage].then(^(MHImage* primaryImage) {
    NSString* url = primaryImage.large.url;
    // Download image at `url`.

CoreHound does its best to ensure these fetches are fast. Typically all the data will be cached, so these requests will be (almost) instantaneous. Only if absolutely required will CoreHound make a network request to get the data.

Sometimes we want to be notified anytime an MHObject‘s properties change. All MHObject properties are KVO-compliant:

NOTE: CoreHound has no thread affinity for KVO notifications. This means that all KVO notifications will be posted from background threads. If you need to tie KVO notifications to UI updates, make sure to dispatch to the main thread when the change notifications occur.

CoreHound is built for large datasets

Since there are lots of connections between objects in The Entertainment Graph, all methods that return other MHObjects take advantage of paging. That means you will only get a subset of results. If you need more, you can fetch more, one page at a time.

The MHPagedResponse class encapsulates a page of results. You can use the content property to access the results of that page:

[movie fetchContributors].then(^(MHPagedResponse* response) {
    NSArray* firstPageResults = response.content;

If you need to access the next page just call -fetchNext on the paged response:

[movie fetchContributors].then(^(MHPagedResponse* firstPage) {
    // Access firstPage.content
    return [response fetchNext];
}).then(^(MHPagedResponse* secondPage) {
     // Access secondPage.content

Searching The Entertainment Graph

To perform searches against The Entertainment Graph, use the MHSearch class:

[MHSearch fetchResultsForSearchTerm:@"The Usual Suspects"
scope:MHSearchScopeMovie].then(^(MHPagedResponse* response) {
    MHObject* firstResult = response.content.firstObject;
    NSLog(@"Found %@",;

Search results are just standard MHObjects, so you can interact with them like you would an MHObject you got back from fetchContributors.

Exploring relations between content

When exploring connections between content, just getting back MHObjects would be limiting. We need to know information about the relationship between the two MHObjects. Consider fetching the contributors for a movie. If all we got back was the MHContributors, we wouldn’t know how that person contributed to the movie. Were they the director, an actor, or produced the movie?

To capture this additional information, we use an MHContext object. Each entry in an MHPagedResponse is an MHRelationalPair, which combines both an MHObject and an MHContext.

[movie fetchContributors].then(^(MHPagedResponse* response) {
    NSArray* firstPageResults = response.content;
    for (MHRelationalPair* pair in firstPageResults) {
       MHObject* obj = pair.object;
       MHContext* ctxt = pair.context;

Acting on Behalf of a User

Entertainment is only part of The Entertainment Graph. Users bring social interaction and knowledge to the graph. CoreHound lets you authenticate on behalf of the user and take social actions on media, create collections, or interact with other users.

Logging in a user

CoreHound offers two ways to log in a user: User OAuth and Enterprise Auth. Most applications will use User OAuth. Enterprise partners can opt-in to an Enterprise Auth flow.

Logging in using User OAuth

Coming soon…

Logging in using Enterprise Auth

Enterprise Auth allows you to directly log a user in using their username and password. You should prompt the user for their username and password and then call the -loginWithUsername:password method on MHLoginSession:

[MHLoginSession loginWithUsername:usernameField.text
                         password:passwordField.text].then(^(MHUser* user){
    // User succesfully logged in
}).catch(^(NSError* error) {
    // Show the user an error

After a succesful login, CoreHound will securely store the user’s credentials to the Keychain. Because of this, you no longer need to store the user’s credentials. You should not store the user’s credentials anywhere!

Once a user has succesfully logged in once, on their next visit to your app, you should try to automatically log in for them.

[MHLoginSession loginUsingSavedCredentials].then(^{
    // User succesfully logged in
}).catch(^(NSError* error) {
    if ([error.domain isEqualToString:MHErrorDomain]) {
        if (error.code == MHLoginSessionNoSavedCredentialsError) {
            // User has no saved credentials
            // in the keychain.
        else if (error.code == MHLoginSessionInvalidCredentialsError) {
            // The stored credentials are no longer valid.
            // The user may have changed them elsewhere.

Once a user is logged in, you can access the currently logged in user via the MHLoginSession:

MHUser* currentUser = [MHLoginSession currentUser];

Creating users in Enterprise Auth

To create a new user, you call the MHUser create method. After the creation promise resolves, you can log the user in using MHLoginSession.

[MHUser createWithUsername:usernameField.text
    return [MHLoginSession loginWithUsername:usernameField.text
    // At this point, you no longer need to store the
    // username or password. You should actively stop
    // storing them, to ensure the user's security.
}).then(^(MHLoginSession* session) {
    // At this point the user is now logged in.
    // You can upload a profile image if you'd like
    return [session.user setProfileImage:userImage];

Login/Logout Notifications

CoreHound emits login and logout notifications if you want to listen for these events in a decoupled manner:

// Set up notification observer for login
[[NSNotificationCenter defaultCenter] addObserver:self

// Set up notification observer for logout
[[NSNotificationCenter defaultCenter] addObserver:self

Application OAuth

If your application does not require a logged-in user, then you do not need to perform User OAuth or Enterprise Auth. Instead, you need to perform Application OAuth to access the MediaHound API. You must first have your Client ID and Client Secret, which you can get from the MediaHound Developer Portal.

[[MHSDK sharedSDK] configureWithClientId:@"YOUR CLIENT ID"
                            clientSecret:@"YOUR CLIENT SECRET"];

This method returns a promise, which resolves when the SDK has been succesfully configured. You must not call into CoreHound, until this promise has resolved.

CoreHound provides meaningful suggestions

From any media content, you can find other related media content. Given an MHMedia, simply call fetchRelated:

[movie fetchRelated].then(^(MHPagedResponse* response) {
    MHMedia* firstRelated = response.content.firstObject;

If you want to find related content to multiple MHMedia, then you can use:

MHMovie* savingPrivateRyan = /* */;
MHMovie* theUsualSuspects = /* */;
[MHMedia fetchRelatedTo:@[savingPrivateRyan, theUsualSuspects]];

CoreHound uses flexible networking

CoreHound uses the network extensively to asynchronously provide data and results as you request it. For advanced use cases, though, you need fine-grain control over how CoreHound requests are scheduled compared to your own networking requests. CoreHound exposes a clear API for controlling caching, priority, cancelation, and reprioritization. This networking infrastructure is provided by Avenue, a general networking library (built upon AFNetworking) that you can use for all network requests in your app.

All CoreHound fetch APIs have a version that takes 3 parameters:

  • Forced: whether to use a cached version if available
  • Priority: how to schedule this request compared to other concurrent network requests
  • Network Token: a token which allows cancelation and priority changes

In the following example, we fetch a movie’s contributors, explicitly ignoring the cache. We also prioritize this request as Low, meaning it will only execute after all High priority requests finish.

[movie fetchContributorsForced:YES
                  networkToken:nil].then(^(MHPagedResponse* response) {
    // use the results

And in the following example, we’ve created a AVENetworkToken and passed it into the -fetchContributorsForced:priority:networkToken method. Afterwards, we call -cancel on the token, and the network request will be cancelled (if it has not already completed).

AVENetworkToken* token = [[AVENetworkToken alloc] init];
[movie fetchContributorsForced:YES
                  networkToken:token].then(^(MHPagedResponse* response) {
    // use the results
[token cancel];


CoreHound is available under the Apache License 2.0. See the LICENSE file for more info.

Latest podspec

    "name": "CoreHound",
    "version": "0.3.1",
    "summary": "The MediaHound iOS SDK",
    "homepage": "",
    "license": "Apache",
    "authors": "MediaHound",
    "social_media_url": "",
    "source": {
        "git": "",
        "tag": "0.3.1"
    "platforms": {
        "ios": "8.0"
    "requires_arc": true,
    "source_files": "Pod/**/*.{h,m}",
    "private_header_files": [
    "dependencies": {
        "AFNetworking": [
            "~> 2.6"
        "AtSugar": [
            "~> 0.1"
        "Avenue": [
            "~> 0.4"
        "AvenueFetcher": [
            "~> 0.4"
        "JSONModel": [
            "~> 1.1.2"
        "PromiseKit/CorePromise": [
            "~> 3.0"
        "UICKeyChainStore": [
            "~> 2.0"

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