How can an iPhone access another non-iPhone device over wireless or Bluetooth?

I'm trying to figure out if an iPhone can connect to another non-iPhone device over wireless or Bluetooth and have seen conflicting information. Much of what I've found was before version 3.0 of the SDK came out, when it certainly wasn't possible. Looking at Stack Overflow questions, like Can the iPhone 3.0 SDK provide full access to Bluetooth devices (headsets)? mention you can't connect to an arbitrary device unless if it's part of the "Works for iPhone" device. Do I need hardware that is part of this program?

Looking through the Apple documentation, Peer-to-Peer Connectivity, it mentions connecting two iPhones, not an iPhone to another Bluetooth device. Then there are articles like iPhone SDK focus: Bluetooth enhancements that includes this quote

...and with the newly-announced "standard support" should allow file transfer between the iPhone and a computer, as well as between nearby iPhones

Another Stack Overflow question, GameKit in iPhone SDK 3.0, mentions Bonjour, and the Apple documentation for Bonjour talks about connecting to Bonjour devices, but can an iPhone connect to any Bonjour device? Does it have to have a Wi-Fi connection, or can it use Bluetooth?

Even if I could use Bluetooth to connect to another device, it won't be available on first generation iPhones and iTouches, I believe. Is that correct? I'm thinking of an iPhone application that would need to communicate with other non-iPhone devices in the area, probably using Bluetooth, but possibly a direct wireless connection. What are the possibilities and limitations of this approach? Is it not possible to have an iPhone connect to an arbitrary Bluetooth device? Does the other device have to be on a wireless Bonjour network that? I'm trying to figure out if it's even possible for this to work or if it's not worth the effort.

Solution 1:

The only way to communicate with other Bluetooth devices via the External Accessory framework in iPhone OS 3.0 is if they are in the Made for iPod accessory program. Even though they communicate through standard Bluetooth connections, accessories need special hardware in order to process the data stream coming from the iPhone / iPod touch. Unfortunately, this means that your idea of communicating with generic Bluetooth devices won't work on iPhone OS 3.0.

If the devices you want to talk to are Bonjour-discoverable via Wi-Fi, they don't need to be part of the Made for iPod program. However, that doesn't sound like your case.

Third-party developers in the near future may produce dongles that connect through the 30-pin dock port and give access to existing Bluetooth devices. If these developers opened up their communication protocol, that might enable your goal of communicating with these devices.

Solution 2:

You can use NSStream for opening IPv4/IPv6 sockets on the iPhone. The devices to which you're connecting do not have to be iPhones or use Wi-Fi necessarily. Because of how network communication protocols are laid out, you simply don't have to care what kind of device your iPhone is communicating with.

Bonjour, on the other hand, uses NSStream internally. It's basically a nifty little wrapper which allows for auto-discovery. You need the Bonjour protocol installed on all devices which you want to participate in the auto-discovery process. There is even an implementation for Windows.