From Nordic: Announcing nRF Connect 2.0 for iOS

Symmetry Electronics Team in Blogs on November 01, 2019

About Symmetry Electronics Team

Established in 1998, Symmetry Electronics is a focused global distributor of wireless connectivity solutions, sensors, and audio-video technologies. Offering comprehensive design support and available-to-ship inventory, Symmetry is committed to helping engineers accelerate time to market, reduce costs, and offer modern solutions for their IoT designs. Acquired by Berkshire Hathaway company, TTI, Inc. in 2017, Symmetry Electronics is part of the Exponential Technology Group (XTG) – a supergroup of electronic component distributors and engineering services firms working together to advance the electronics industry. For more information, visit www.symmetryelectronics.com.

For the past ten months, we’ve been busy, hunkering down in front of our keyboards, keeping the blinds down, shooting mean looks at our bosses whenever they dared interrupt us. And of course, all the while, we were blasting some Linkin Park through our Beats headphones, making sure our energy levels were kept flying high. We needed it. Because every single time a new email hit our inbox, we felt the pain of having to ignore one of your many requests, that went along the lines of:

I’m missing [INSERT FAVOURITE FEATURE] from the Android app in iOS.
The current version of nRF Connect is good, but could you please fix [INSERT BUG]?
Help? The app is crashing for me!

It wasn’t easy for us. We didn’t intend to ignore you, or disrespect you. All we knew was that we were working on something new, which we hoped would turn out to be really great. After all, we deemed it unnecessary to just promise that a brand-new version of nRF Connect was coming, without being able to commit to a release date. In other words: we didn’t want to be just another case of vaporware.

We did that in the hopes that one day, we could proudly announce that it was ready: that all of our hard work, together with your continuous support and use of nRF Connect for iOS, had yielded a fantastic new Bluetooth Low Energy tool for you to use. And that day, just so happens to be today. Right now. So please, stop reading and go get it from the App Store!

But if you want to keep reading to discover what’s new, be our guest :)

Learning From the Past

nRF Connect for iOS 2.0 had two main influences behind its design. The first and most evident one, was its predecessor, nRF Connect 1.x. This is the app you know and love, and have depended upon time, and time again, to scan and work with your nearby Bluetooth LE peripherals. As such, making a brand-new app had to both seem familiar with our existing users, as well as make noticeable improvements upon it that made it easier, and not harder, to use. Whether it’s written in Smalltalk, Objective-C, Swift 5.1, uses nibs, Storyboards, or SwiftUI, is of little importance to you: all is rendered useless if you can’t feel that the app works and makes your life better with it in your device.

nRF Connect for iOS 1.8.8

Out of the box, our first change was focused on navigation and discoverability. Although there is a button on the top-left corner to access the RSSI Graphs in nRF Connect 1.x, we felt this had two major drawbacks:

Phones are getting noticeably bigger, so we should strive to remove as many parts of the User Interface from the topmost sections of the app as possible.
The swipe-right to open behavior did not seem discoverable enough to us. This is a concern we took from nRF Connect for Android too, where we’re currently lacking any visual indication of the existence of these graphs, unless the app is running in tablet form.

NEW! nRF Connect for iOS 2.0

This pushed us to improve upon both of these situations. And the end result is that we pay an homage to how nRF Connect used to work, but, making it a lot more discoverable. To the point that it’s now impossible not to know that there’s an RSSI Graph view in the app. Granted, you cannot swipe anymore to switch between the Scanner List and RSSI Graph, but it’s a lot easier now to move between them because they’re independent, though related, tabs. And, because we keep a shorthand version of the Scanner list on the left side of the RSSI Graph screen, you don’t lose track of the items you’re watching over. This plays very well with how both key screens are positioned within the app’s navigation: because the items are on the left, it can feel like the Scanner list, which is the leftmost tab, is “breaking into” our RSSI screen, which sits to its right. Neat, if you ask us.

Of course, that is not all. If you were a power user of nRF Connect’s 1.x, you’ll immediately be surprised by 2.0’s improved performance regarding the drawing algorithm for RSSI Graphs, no matter the age of your device. This is achieved through a combination of background threads (via Grand Central Dispatch), a windowing algorithm to average-out the broadcast interval of the scanned devices, inspired by the TCP protocol, and the use of the Core Animation Display Link API. A CADisplayLink works like a Timer that’s synchronised with the refresh rate of your device’s display, meaning you’ll get called at the appropriate time for your users to see your updates, without clogging your CPU too much. Because CADisplayLink was designed to keep the device’s frame-rate smooth at all times, prioritising user interactions, you’ll see that the graph stops updating the moment you interact with the app, such as when scrolling through the list of devices. It’s a minor inconvenience for sure, but we think the benefits outweigh the drawbacks.