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Hullo, folks! I'grand Kyle Erf, the technical managing director at Moving Pieces Interactive, a minor studio in Brooklyn, New York. Nosotros're the creators of Dodo Peak, a modern take on beloved arcade platformers from the 1980s.

Earlier this year, we had the privilege of releasing Dullard Peak as one of the launch titles on Apple's new Arcade subscription service. Ane of the main selling points for Apple Arcade is that games work across all devices, including Macs. To release Dodo Summit on Apple tree Arcade, we had to integrate with Apple's Mac App Store ecosystem along with Apple services like iCloud and Game Middle.

In that location are skilful reasons why anyone targeting a Mac release should consider doing this:

• On the Mac App Shop, your game can organically accomplish players who aren't plugged into more games-focused digital stores.
• Using iCloud or Game Eye to handle things like leaderboards and cloud saves ways you tin rely on free, trusted, first-political party services rather than integrating third-party infrastructure into your app.
• Apple tree Arcade requires Game Center and iCloud every bit part of its hope of cloud saves accessible across devices.

You'll exist happy to learn Unreal supports Game Center and iCloud for iOS targets out of the box. The bad news is that the same support isn't built-in for builds targeting macOS. Until recently, targeting your Unreal game to the Mac App Store was a much less common use case.

Fortunately, anyone can manually work around these feature gaps. Over the last few months, I accidentally became an good on integrating Unreal games with Apple services on Mac, and I'd similar to get all that cognition out there then you don't take to piece it together yourself. This guide will embrace both how to integrate your Mac game with Apple services and how to package your game for the Mac App Store.

Setting up your Mac app in the Apple developer portal

The showtime step toward getting your game working with Apple services and upward on the Mac App Store is configuring your app in Apple's backend. There are plenty of guides that evidence you how to practice this, merely for the sake of completion, hither is a quick checklist of what you'll accept to do:

1. Join the Apple Developer Plan (this costs a yearly $99 fee).
2. Create your app via the Identifiers section of the Certificates, Identifiers & Profiles folio.
   1. Give your app a useful package ID like "com.mycompany.mygame".
   2. Enable iCloud and Game Center capabilities, plus any others you want.
   3. Note: if you already take a working app identifier for an iOS version of your game, you lot can motorcar-generate a Mac identifier for information technology by selecting the "Mac" capability from the iOS app identifier's settings.
3. Create certificates for your account in the Certificates section of the Certificates, Identifiers & Profiles folio.
   1. Locally, create a Document Signing Request.
   2. Apply information technology to create and download certificates for:
      1. Mac Development
      2. Mac App Distribution
      3. Mac Installer Distribution
4. Add whatsoever exam or development Macs y'all ain in the Devices section of the Certificates, Identifiers & Profiles page.
   1. You can find Mac UDIDs via the System Report characteristic.
5. (Optional) Create an iCloud container via the Identifiers department of the Certificates, Identifiers & Profiles page.
   1. Edit your app identifier and assign the container using the push button side by side to the iCloud capability.
6. Create and download relevant provisioning profiles.
   1. Create a Mac Evolution provisioning profile.
      1. Be sure to select your newly-created app identifier, certificates, and devices.
   2. Create a Mac App Shop provisioning profile.
7. Create a new macOS app in App Shop Connect and select your new parcel identifier.
8. Open your project in Unreal. In your project settings, get to Platforms > iOS, and set your Package Identifier to be your new Bundle ID.

That'south the boring part. This volition all come in handy after when it comes fourth dimension to bundle or examination your game. The next department will become over how to actually write lawmaking effectually features like Game Centre and iCloud.

Integrating your Mac game with Apple APIs

Since the engine doesn't accept the hooks y'all need for your games to talk to iCloud or Game Heart on macOS, you'll accept to implement them yourself. A quick scan of Apple tree's documentation shows us that the only mode to crack the shell of their operating arrangement APIs and become at the nutrient-rich center is by using Objective-C or Swift.

That'south a petty scary to hear, since Unreal uses C++. So how do you do it? Are you in for a nasty time compiling and linking static libraries? Nope!

You tin can get effectually it the same way the Unreal Engine source does: with a powerful, little-publicized feature of Xcode called Objective-C++.

What is Objective-C++?

Objective-C++ is what information technology sounds like: the power to inline Objective-C code inside of your C++ (or vice versa). Both C++ and Objective-C are supersets of C, meaning they back up all of the syntax of vanilla C plus boosted features. While in that location are cases where the ii languages are at odds, for the most part, using both of them together in Xcode simply works.

For folks looking for a more in-depth guide to Objective-C++, I'd recommend this Medium commodity. There are a few dangers to avoid around Objective-C'southward reference counting-based memory direction, but for the nearly office, things just piece of work. For at present, let's become to what you came here for: code samples.

Supporting Game Middle on Mac

Apple has their own guides on how to code for Game Center, just the short version goes something similar:

1. Cosign your role player
2. Apply that authenticated role player to make calls to achievements, leaderboards, so on

Before you can compile any of the following code, yous'll need to surface the requisite libraries to your package via Unreal'southward build organization. In your game's Build.cs file, add the following logic to your constructor:

                              if (Target.Platform == UnrealTargetPlatform.Mac) {             PublicFrameworks.AddRange(new string[]{"GameKit"});         }            

Here'south a sample of how 1 might authenticate their player using Objective-C++. Note I am passing an Objective-C callback to the authenticateHandler, just the code inside that callback function tin can comprise C++.

              #include <GameKit/GameKit.h>  void UMyBlueprintFunctionLibrary::GameCenterSignIn() { #if WITH_EDITOR     // do non run in editor #elif PLATFORM_MAC     // asynchronously log into GameCenter. In your code I recommend wiring this up     // with delegates or UBlueprintAsyncActionBase so that you can handle cases     // where logging in takes a while.     dispatch_async(dispatch_get_main_queue(), ^{         [[GKLocalPlayer localPlayer]          setAuthenticateHandler:^(NSViewController *_Nonnull viewController, NSError *error) {              if ([[GKLocalPlayer localPlayer] isAuthenticated])              {                  // Success                  return;              }              if (error)              {                  // Failure              }              else if (viewController)              {                  // display login                  GKDialogController *presenter = [GKDialogController sharedDialogController];                  presenter.parentWindow = [NSApp keyWindow];                  [presenter presentViewController:(NSViewController * _Nonnull) viewController];              }          }];     }); 

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