Chapter 2. Understanding Apple Watch

During the launch of WWDC 2015, Apple introduced a new addition to their product lineup called Apple Watch, which runs the new watchOS platform. It has been designed and built from the ground up while borrowing design characteristics from iOS 8, with features and apps that take advantage of the hardware within the Apple Watch device.

Apple Watch comes with a variety of apps, such as Activity and Workout, which read data from the accelerometer and the heart rate sensor, while other apps contain communication features that enable users to send sketches, heartbeats, as well as animated emojis. Notification messages are sent from the iPhone device and delivered to Apple Watch with small haptic taps on the wrist, while Glances offers small pieces of information that can easily be digested in a few seconds without having to pull your iPhone out of your pocket.

Since the release of Apple Watch, the Apple developer community has embraced this new piece of technology...

Introduction to the WatchKit platform

This section provides you with an overview of the WatchKit platform, which is a fundamental part of Apple Watch. When developing apps for Apple Watch, it takes advantage of the WatchKit framework that happens to be included as part of the iOS SDK, and both are embedded into the watchOS and iOS operating systems.

The WatchKit framework contains the necessary classes that provide the underlying functionality for both the WatchKit extension and the WatchKit application and is responsible for handling all of the communication between the WatchKit extension that runs on the iPhone device and its corresponding WatchKit application that is installed on Apple Watch.

Whenever you begin developing Apple Watch apps, you will notice that your project contains a number of different targets that make use of the WatchKit platform.

Note

A target is the final end product that is created by your application, and these can be either an app, a framework, or even a static library...

Apple Watch Human Interface Guidelines

When designing apps for Apple Watch, these apps need to be designed differently from how you would go about designing apps for phone or tablets as they provide a different user experience. It is important to keep in mind and follow the Apple Watch interface guidelines documentation that Apple provides.

This document describes guidelines and principles that can help you design consistent user interfaces and experiences for your Watch apps as well as ensure that your applications are running efficiently within the Apple Watch platform. You need to consider the screen sizes for your custom layouts as well as the ease of use your app brings to the platform. Other areas are covered to ensure the consistency of your application while navigating from screen to screen; the principles of designing good user interfaces are also covered.

There is also information related to the proper use and appearance of views and controls for navigation, alerts, notifications...

What's new in watchOS 2

In this section, we will take a look at the differences between watchOS 1.0 and watchOS 2. One of the biggest highlights of the watchOS 2 platform is the support for native apps, which means that the apps will be able to run entirely on Apple Watch without having to rely on iPhone. This allows developers to access the device's built-in heart rate sensor, the Taptic feedback engine, accelerometer, and microphone with the ability to build custom watch faces to display information within the Apple Watch face.

The watchOS 2 version comes with two brand new watch faces called Time Travel, which displays information about future complications, such as weather and calendar events, and the Nightstand mode, which is activated when Apple Watch charges. There are also several improvements to Mail as well as support for FaceTime Audio, and it supports multiple colors for sketches and lets users add more than twelve friends to their list of contacts.

Apple has also made several...

Summary

In this chapter, you were introduced to the architecture behind the WatchKit platform, and we discussed how the WatchKit framework is responsible for handling the communication between Apple Watch and the paired iPhone over Bluetooth as well as the differences between the WatchKit app and extension. We then moved on to discussing the WatchKit application life cycle and took an overview of what happens when an app is launched on Apple Watch and the associated classes and methods that are called before taking a look at some of the limitations that the WatchKit framework currently has.

In our next step, you learned about Apple Watch Human Interface Guidelines to ensure that we develop our apps in accordance with Apple's best practices. Finally, we got an insight into some of the great new features and additions that are coming as part of the watchOS 2 platform.

In the next chapter, you will learn how to work with Xcode's Interface Builder and some of the controls that come with the WatchKit...