THE BLOG
02/06/2015 07:57 BST | Updated 01/06/2016 06:59 BST

Building an Apple Watch App: An Insider's Guide

"An expensive convenience gadget", says TechRadar. "A possibly time-saving companion", but "more like a fashionable toy than a necessary tool" is CNet's verdict. Bloomberg predict "you'll want one, but you don't need one".

Most critics agree that, in its current state, the Apple Watch is not as fundamental to our tech-powered lives as the MacBook, iPhone or iPad. But that's not to say that it can't be incredibly useful.

At JustPark, the parking app and website I founded in 2006, we quickly realised that a Watch version of our product could bring great value to our drivers - but also recognised that, when it comes to developing an app for the Watch, less is most definitely more.

The key benefits of the Apple Watch are speed and discretion.

Its unobtrusive display gives the wearer instant access to information and lets them respond quickly, with minimum effort and disruption. The Watch is especially valuable in situations where efficiency is of the essence - whether that's keeping track of incoming emails during a meeting, checking transport information whilst on the move, or extending your parking if you're running late.

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But, for all its efficiency, the Watch is not a replacement for the iPhone - at least not yet. With a 42mm screen and no typing function, in-depth interactions are still far easier to complete on your iPhone.

When it comes to building a Watch app, the cliched advice to 'keep it simple' has never been more true.

There's no point in trying to replicate an iPhone app on the Watch - their capabilities are fundamentally different. If something's easier on the iPhone, leave it to the iPhone app.

Instead, identify one or two components of your iPhone app that would be more convenient to have on your wrist, and adapt them for the smaller screen. Remember: a Watch app should add value for the user as an extension of the iPhone app, rather than as a pale imitation of it.

It might sound obvious, but a Watch app needs to be useful.

At JustPark, we decided that being able to check the amount of time remaining on a booking - and extend it if necessary - would be the handiest feature to have on the Watch.

The process of making a booking is more easily accomplished on the iPhone - but being able to keep tabs on the time that your booking ends and see how long it'll take you to walk back to your car is genuinely useful information to have on the Watch. When your booking only has 30 minutes to go, you'll be prompted to extend it with a couple of taps of your wrist.

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Uber have executed the minimalist approach brilliantly with their Watch app, which has just one feature - tap the screen and it sends a car to your location, displaying info on your driver and his whereabouts as you wait. Anything more complicated than this is left to the iPhone app - in Uber's case, choosing your default service type, rating drivers and changing profile settings.

The CNN app is another great example of how to share this functionality 'load' elegantly between Watch and Phone: the Watch alerts you to breaking news and displays headlines to keep you constantly up-to-date; then, if something catches your attention and you want to learn more, you can tap to save the story for later or open it in full on your iPhone.

The device's in-built features add great value to any Watch app.

The Watch's 'Taptic Engine' - which causes it to vibrate gently with incoming alerts and notifications - is a really exciting feature. With JustPark, you get a digital 'tap' on your wrist when your booking is about to expire, prompting you to extend if you need more time. Similarly, CommitTo3 - a productivity app for logging daily goals - gives you regular nudges throughout the day to remind you where your focus should be.

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Another great feature is the Glance view - an easily-digestible slideshow of information from each of your apps. With one glance at your wrist, Yahoo Weather will give you current temperature and conditions; swipe left, and Citymapper will tell you if there are any disruptions to public transport services; swipe again, and JustPark will tell you when your parking expires and how long it will take to walk to your car.

It's useful and slick - but it's not an iPhone.

Although it remains to be seen whether it will ever challenge the iPhone for functionality, the Watch undoubtedly adds an extra element of efficiency to any iOS app.

But the Watch should be understood as just that - an addition to the iPhone, not a replacement. Developers should keep this principle at the forefront of their minds when building apps for the device.