Hardware Features of the Apple Watch
This article provides an overview of the numerous input and output devices included in the Apple Watch.
Interacting with the Apple Watch
As you can imagine, it’s difficult to operate a device as small as a watch with fingers alone (see my article Prototyping WatchKit Apps on how to get an idea of the size of the Apple Watch without actually owning one). For this reason, Apple provides a number of ways to interact with the watch in addition to a multi-touch screen.
The touch screen itself features 272 x 340 pixels (38mm)/ 312 x 390 pixels (42mm) at 326 dpi (@2x resolution) and is made out of Sapphire crystal or strengthened Ion-X glass (Apple Watch Sport).
The supported gestures are simplified compared to the iPhone. For example, there’s no pinch to zoom because of the limited size to execute such a gesture. However, you can do the standard one and two-finger gestures like tapping, scrolling and panning as you are used to.
A new feature when compared to the iPhone is the touch screen’s ability to distinguished between light and hard presses on its surface. Apple calls the latter feature Force Touch and it triggers an app’s menu screen. Also, the screen detects whether it’s covered by your hand, which is used to mute an incoming call, for example.
Hardware controls accessible from the front of the watch include the Digital Crown, a dial that can be rotated and pushed and a simple button right below the crown. The Digital Crown is used to zoom content, scroll lists and make selections whereas the button is a shortcut to launch Friends, an app to communicate with your closest friends.
If you want to use the Apple Watch without even lifting a finger, you can operate the watch with Siri. This works in a similar way to the iPhone where Siri interprets your voice commands and provides answers or starts apps. You can also use the voice recognition feature of the watch to enter text if needed.
Note that apps don’t have direct access to gesture handling and input controls. Instead, functionality is hardwired to effect certain actions. I expect future SDKs to provide more advanced gesture handling, but for now, the purpose of each gesture and button has been preselected by Apple.
Additional Sensors and Actuators
There are also a number of hardware features that work without direct user interaction.
Mounted on the back of the watch is a sensor that measures your heart rate using infrared and visible-light LEDs and photodiodes. With obvious applications for fitness apps, this sensor also simplifies PIN and password input: as long as it can detect skin contact, you don’t have to authenticate again.
The back of the watch is also the place where you attach an inductive charging connector, which will snap into place with magnets similar to the MagSafe connector built into a MacBook.
The built-in accelerometer measures body movements (to count steps, for example) and will automatically turn the display on and off when lifting your wrist. Wikipedia reports that the Apple Watch includes a gyroscope and barometer although I couldn’t find any mention of it in Apple’s documentation.
In interesting feature is a haptic feedback device called Taptic Engine. It combines vibration with audio cues to generate a sophisticated tactile feedback device. Sample use cases mentioned by Apple include map navigation, where a tap to the right or left of your wrist steers you in the right direction, and getting someone’s attention with a gentle tap.
Connectivity
For now, the Apple Watch requires an iPhone to connect to the Internet and receive GPS location updates. The latter makes the watch somewhat less useful to sports enthusiasts because it will not be possible to track the distance you run by its own.
The Apple Watch actually does support a limited form of Wi-Fi, but only as part of the supported Bluetooth spec to connect with your iPhone. So far, app developers cannot create standalone apps so that all dynamically updated data that’s displayed on your phone needs to travel through this connection from your iPhone to the watch.
Based on the announcement that you will be able to use Apple Pay with your watch, it follows that the watch will also include NFC connectivity. Like the NFC support on iPhone this is not directly accessible by app developers.
If you liked this article, you might be interested in my other articles in this series about Practical WatchKit Development:
- Prototyping WatchKit Apps
- Hardware Features of the Apple Watch
- Interacting with WatchKit Apps
- Essential Technologies for Developing WatchKit Apps
If you have any questions about this article, feel free to contact me on Twitter.
