Series: Improving an SDK With Core Bluetooth

This series will pick up where the last series left off. It should be fairly quick, relatively.

If we do a recap of our conclusion, we were left with the following list of “TODOs”:

1. The error handling is primitive, at best.
   We didn’t really do much to capture errors. We have the ability in the apps to catch and display them, but we didn’t take advantage of this in the SDK.
   This was mostly because I wanted to keep the lesson as simple and to-the-point as possible. If it were a “shipping” SDK, error handling would have been one of my first priorities.
2. The Central “locks up” Peripherals.
   Because we connect, then hold the connection, a Peripheral is dedicated to a Central. It might be nice to allow a Peripheral to be used by multiple Centrals.
3. We could put the entire Peripheral functionality inside the SDK.
   We could remove the ability to select a response, thus pretty much obviating the need for user intervention. It could be entirely possible to simply do the response automatically in the SDK, and report the results to the Peripheral user.
4. It would be nice to know whether or not the question made it to the Peripheral.
   At the moment, we have the .writeWithoutResponse property set on the question, so we aren’t sure that the question made it to the Peripheral. We can ask the Peripheral to let us know if the question made it.
5. This barely scratches the surface of Bluetooth Programming.
   Agreed. The purpose of this series (so far) has been to introduce Core Bluetooth. I expect to be exploring Bluetooth programming much further, and will use this SDK as the vehicle for that.
6. The iOS app doesn’t clean up after itself very well.
   The Mac app closes all resource connections when it quits, but the iOS app can “hold the connection open.” That’s really something that would require work on the apps, as well as the SDK.
7. We’re Not Sure Who’s Asking the Question.
   It would be nice to have a label on the Peripheral screen that showed who was asking the question.
8. The App is Pathetic
   Yeah…It’s just enough to show that the SDK works. We can do better.
9. We could explore Bluetooth “Classic” (BR/EDR) with this project.
   We’re using BLE for this, and it’s really the perfect type of task for BLE, but this would also be something that could be done with Bluetooth “Classic.”

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Before we dive in, let’s take a bit of time to review how Core Bluetooth handles communications between Centrals and Peripherals.

THE PERIPHERAL MANAGES THE SERVICES, CHARACTERISTICS, AND DESCRIPTORS

As was noted in the previous series, the Peripheral is responsible for setting the values of Characteristics, and managing the lifetimes of Services.

The Central will have CBPeripheral, CBService, CBCharacteristic, and CBDescriptor instances, but they will all be read-only “proxies” of the CBPeripheralManager, CBMutableService, CBMutableCharacteristic, and CBMutableDescriptor instances managed by the Peripheral.

What’s nice, is that Core Bluetooth abstracts all the nitty-gritty of Bluetooth transport for us, and gives us a fairly manageable API.

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The goal of this exercise is to have the Peripheral (the “Magic 8-Ball” device) respond immediately, and completely randomly, to questions asked by the Central; without presenting a list of questions to the user of the Peripheral Mode app.

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THIS AIN’T GONNA HAPPEN

Here’s why.

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One thing that we can do, is make sure that the Peripheral actually gets our question. Right now, we simply rely on the fact that we sent it to confirm its receipt.

We would like to wait until the Peripheral actually tells us that it received the question before we assume that it has been sent.

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We’ve actually already done most of the work for this item, but let’s see if there’s anything more we can do (at this point).

Remember that one of our current restrictions is to have no changes in the apps, themselves, so anything that we do has to be in the SDK-src directory. At this point, the Apps-src directory is still at the same version it was when we started (Tag itcb-09).

Everything that we’ve done, to this point, has been in the SDK.

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This was a relatively short exercise, compared to the first series, and we made all of the changes inside the SDK-src directory.

Here is our ending Repo tag.

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