Introducing the “Welcome to Xojo” Bundle!

New to Xojo and looking for guidance? We've put together a terrific bundle to welcome you! Xojo Bundle

This bundle includes six back issues of the magazine -- all of year 21 in printed book and digital formats -- plus a one-year subscription (beginning with 22.1) so you'll be learning all about Xojo for the next year. It's the perfect way to get started programming with Xojo. And you save as much as $35 over the non-bundle price!

This offer is only available for a limited time as supplies are limited, so hurry today and order this special bundle before the offer goes away!

Article Preview

Buy Now

Issue 12.4 ('Game Center')
Instant purchase and download via GumRoad!


Writing OS X Apps for Game Center

Getting started by authenticating the local player with the Game Center Sandbox testing facility

Issue: 12.4 (July/August 2014)
Author: Tom Baumgartner
Author Bio: Tom is retired and enjoys programming in Xojo, especially during the Canadian winter when he can't golf, fish, or play tennis. He does enjoy curling in the winter.
Article Description: No description available.
Article Length (in bytes): 21,109
Starting Page Number: 23
Article Number: 12407
Resource File(s):

Download Icon 12407project.zip Updated: 2014-09-05 10:57:37

Related Web Link(s):


Excerpt of article text...

I like turn-based board games. When I can't find an opponent in the house I like to play against friends on the computer. I was excited when Apple introduced Game Center on the Mac and soon started to try to write my own Mac games that could use Game Center. That has turned out to be quite a project. This article and, hopefully, subsequent articles will guide you through the process of making a game interoperate with Game Center.

Developing a Mac OS X game for Game Center is more involved than just building the application in Xojo. In fact, although there are many steps in common with the requirements for submitting an app to the Mac App Store, working with Game Center requires additional steps. This series of articles will explain all the steps you must take. This first article will cover the basic setup for testing with Game Center Sandbox test facility and the first step of player authentication. Later articles will cover setting up matches and actual game play.

The Author's Software sidebar lists the software used and their versions when this article was written. Because of the delay between the time this article was written and the time it is published, there may be later versions of the software now available.

Since you are using Xojo for your development environment, you may be as adverse to the Objective-C programming language as I am. There is a price to be paid for not using Apple's Xcode, both in extra expense and in post-build work. Of course, all the programming time you save with Xojo more than compensates for the extra expense and post-build work.

Soon after Game Center was introduced, I asked Christian Schmitz of Monkeybread Software to add GameKit to his Xojo plugins. Christian responded quickly by adding GameKit to his Mountain Lion plugin. He has continued to assist me during this project as we both are learning about GameKit. In fact, a change made in 14.2 pre-release 3 allowed successful player authentication. This plugin version will most likely be in final release by the time you read this article. Go to the Monkeybread website (http://www.monkeybreadsoftware.de) to purchase and download the Xojo plugins. You should buy the Complete package. After downloading the plugins, you need to move the following plugins to the Xojo Plugins folder:

  • Main

...End of Excerpt. Please purchase the magazine to read the full article.