I’m still in the middle of finishing up our Co-op mode for Tilt to Live and coding in the last odds and ends to polish up the UI. The gameplay rules have be finalized and it’s been a hoot to play. Yes, I said hoot. We’ll be playtesting the mode in the coming weeks to do any minor tweaking to the physics and balance.

The wireless P2P GameKit API has been pretty cool to work with. It certainly takes a bit longer to get something tangible out of it because it’s a relatively ‘invisible’ piece of the iOS SDK  (as opposed to Core Animation, UIKit, and the like). Yet there’s always something inside me that goes “that is so damn cool” when I finally see a game running on two separate devices and are interacting with each other.

I’d like to write up a mini post-mortem after the co-op update is done looking back at adding real-time networked play to an iphone game. But for now, the biggest hurdle was realizing that running with the GKPeerPickerController  limited you to only bluetooth. The docs weren’t 100% clear on this and I was beating my head on my desk seeing people claiming GameKit worked over Wi-fi with no issues and I couldn’t get any device to talk to each other without bluetooth. Couple that with a faulty router setting keeping my iDevices from connecting to each other and it was a painful couple of days. In any case, let it be known, that if you wish to support local Wi-Fi and Bluetooth transparently you’ll need your own custom UI outside of GKPeerPickerController for clients connecting a host.

Oh, and the utter joy I experienced when I realized I had to change zero networking code to have it work over w-fi was indescribable. I think I fell in love with GameKit at that point since I was anticipating  a day of refactoring, integrating bonjour directly, and whatever else I had in mind to keep the game-level networking code intact.

For anyone thinking about doing some real-time multiplayer game on the iPhone, the biggest problem you’ll probably face is interference, followed by throughput (when dealing with bluetooth anyway). iPhones are jam packed with so much wireless technology that it seems if the wifi or 3G antenna so much as thinks about sending or receiving data, bluetooth communication suffers horribly.  I’ve had many a game end in death when I received an e-mail or text during gameplay. We originally intended on supporting nothing but bluetooth, but given this type of wildly varying performance we needed to have a fall back solution that was a bit more reliable. Thankfully, GameKit made it easy. While I was hoping I wouldn’t have to code up a custom UI (pictured above) because of GKPeerPickerController’s magic, in the end it added more robust functionality, as well as felt a lot more integrated into the game.