What is the simplest way to connect a device to an iPad from an application?

Question

I am working on a major product release for my company. We are designing a new device that we would like to integrate into an iOS app. (FYI, we have recently been accepted into the Apple MFi program so we are past that step.)

What we desire is to create a hardware/software eco-system where our users can start our iPad app (yes, it is specific to the iPad and the not iPhone or iPod Touch devices) and the application will automatically discover and link up with any close-proximity hardware that we've developed.

This means that I will need to implement some form of device connection process on both the iPad and within the hardware.

Is there any way to code automatic connectivity to a Bluetooth device from within an iOS application?

I am aware of the Core Bluetooth Framework which has this capability, however, it only works with the new iPhone 4S. That's not an option.

I've also researched about the External Accessory Framework, which can be used to connect to external devices whether they are connected via the iPod port or Bluetooth. This is an option but, if my understanding is correct, our hardware must already be paired with iPad before the iOS software can connect to it. This is less than preferable because although many of our devices may not be in immediate vicinity at one point in time, our customers could potentially own 100's devices that they may desire to connect to with our software.

What are my reasonable options or alternatives? The end goal is to provide a very easy means for our users to be able to connect to our devices, from within our software, on an iPad.

NOTE: I MUST NOT jailbreak the iPad or break any Apple TOS agreements.

UPDATE (3-7-2012) I saw today that the 'New iPad' (as it is being officially called) will be Bluetooth 4.0 capable. I assume this means that this iPad device will be able to use the Core Bluetooth Framework. This doesn't immediately solve my problem because we do want remain compatible with at least the "last generation" iPad device, but this is worth pointing out for others who may be looking for such an answer.

Answer 1

You cannot connect an iOS device to a bluetooth device without pairing first. It is purposely built that way by Apple to reduce the likelihood that someone could connect a bluetooth device without the user knowing about it. If pairing each device is unacceptable (and it sounds like it is), and you don't want to develop a dongle, the only remaining path I can see is to make your devices capable of relaying data between them like a mesh network. That way the user would only have to pair with a single device, and that paired unit would relay communications between the other devices and the iPad.

Answer 2

One of your alternatives would be going WiFi (AdHoc or Infrastructure) with Bonjour. For example you would be able to detect the device nearby (if it is maintaining it's own AdHoc then by SSID; if it's in infrastructure network then by service being announced). One big drawback would be that you couldn't connect directly (from app) to the device's network - user would have to do it manually.

As for BT: big drawback is lack of a serial protocol (not implemented in iPhone/iPod/iPad).