watchOS is the mobile operating system of the Apple Watch, developed by Apple Inc. It is based on the iOS operating system and has many similar features. It was released on April 24, 2015, along with the Apple Watch, the only device that runs watchOS. Its API is called WatchKit.
The second version, watchOS 2, included support for native third-party apps and other improvements, and was released on September 21, 2015. The third version, watchOS 3, was released on September 13, 2016, emphasizing better performance and including new watch faces and stock apps. The fourth version, watchOS 4, was released on September 19, 2017. The fifth version, watchOS 5, was announced on June 4, 2018, adding more third-party support and new workouts, along with the “Walkie-Talkie” feature.
The home screen (rendered by and also known as "Carousel") is composed of circular applicationicons, which can be zoomed in and out with the Digital Crown and dragged and launched by touching the display. Many of the apps are miniaturized, simplified versions of their iOS counterparts.
Prior to watchOS 3, Glances provided fast access to a summarized view of the most popular native or third party applications used on Apple Watch. The Glances view was opened with a swipe up gesture from the watch face screen. With watchOS 3, Glances has been replaced by a redesigned Control Center - much like the one in iOS. The friends menu, invoked with the side button, now acts as a dedicated dock for apps.
Different actions and options appear depending on if the user taps or deep presses which an Apple Watch detects with its pressure-sensitive (Force Touch) Display.
For several years now, Apple has been developing its HealthKit product in a bid to change the way people interact with their devices. There is also a thinly veiled attempt to penetrate the lucrative healthcare and wellness industry, which many observers believe to hold huge growth opportunity for Apple. This was confirmed by Jony Ive, Apple's chief designer, in an interview. He said that health was a crucial element in the Apple Watch since the day of its inception and that the developmental trajectory of the hardware and the WatchOS were geared towards health-based capabilities. Ive pointed out that that one of the primary apps that shipped with the first WatchOS allowed users to track and communicate as well as encourage them to move, exercise, and stand. He said:
Many of us have our phones with us all the time, but they aren’t connected to you. Imagine having something this powerful with you at all times, and what opportunities that might present to the user. The opportunity is phenomenal. Particularly when [you] don’t understand just where we are today in terms of technology and capability, but where we are headed.
One of the most recent updates to the watchOS included applications that do not only keep users active but also diagnose illnesses. For example, there is the app called DeepHeart, a deep learning network that can detect atrial fibrillation, hypertension, sleep apnea, and diabetes. It taps the HealthKit platform to collect data, particularly those collected by the Apple Watch's heart sensor.
Allows the Apple Watch to act as a nightstand/alarm clock when the watch is charging at night and is turned horizontally while being placed on a table or other surface. Users can look at the time just by tapping the Digital Crown. When an alarm comes on, the Digital Crown can be used to snooze the alarm and the side button can be used to dismiss it.
New Watch Faces and timekeeping features
New 24 Hour Time-Lapse videos of Hong Kong, London, Mack Lake, New York, Shanghai, and Paris. These watch faces allow users to set the backgrounds of different cities as the user's watch face. As the day moves on, the watch face represents a different time of day in the city. For example, if it is nighttime, the watch will show a skyline of the city at night.
Users can also set a particular photo or their entire photo gallery as the watch face, including support for Live Photos.
A new mode called Time Travel is available in which a user can use the digital crown to scroll forward/backward in time. This allows the user to see upcoming or past calendar events and alarms they have set.
9 new colors to customize watch face, and a new multicolor Modular face.
Third party complications.
Complications will be available from third-party developers which allow users to do things such as check flight status or charging level of electric cars
Initial Release on Apple Watch Series 1 (Dual-Core) and Apple Watch Series 2 (Dual-Core)
Performance and Navigation
Provides faster access to apps by creating a dock which can accommodate up to 10 apps which will keep running in the background for instant access.
The dock can be invoked using the side button next to the digital crown.
Provides support for an all-new Control Center which can be invoked by sliding up from the bottom of the screen.
New Watch Faces.
Adds new watch faces and adds support for switching between them by swiping left/right from the edge of the watch screen.
Adds support for sharing activity with friends using iMessage or other messaging platforms.
Adds support for tracking movement of people in wheelchairs, displaying a "Time to Roll" reminder rather than "Time to Walk" as watchOS 2 did.
It is now possible to see 5 different workout metrics all at once. These include distance, pace, active calories, heart rate, and elapsed time.
Adds support for pausing a workout when stopped at a stoplight.
Support for a new Breathe app which will guide users through a set of deep breaths to help them be more relaxed.
Adds support for the all-new messaging app which will also be present in iOS 10. This includes features such as setting off fireworks, sticking stickers, sharing a secret with invisible ink, or replying in your own handwriting or scribbling letters on the display and letting Apple Watch turn it into text.
Adds support for an all-new Home app which is a centralized place to control all HomeKit accessories.
Adds support for a feature called SOS which allows a person to place emergency calls by holding the side button for 5 seconds.
Alongside macOS Sierra, the Apple Watch running watchOS 3 can now allow users to bypass the unlock screen on their Mac by allowing the Mac to detect their Apple Watch and unlock the Mac.
October 24, 2016; 20 months ago (2016-10-24)
New option to replay bubble and full screen effects in Messages
Messages effects can play with Reduce Motion enabled
Fixes an issue that could cause the notification for Timer complete to be delivered twice
Resolves an issue that could prevent Apple Watch Series 2 from fully charging
Resolves an issue where Activity rings may disappear from the watch face
Fixes an issue that prevented Force Touch options from appearing in some third-party apps.
December 12, 2016; 18 months ago (2016-12-12)
Update withdrawn due to reports of Apple Watches no longer working after the update
Fixes an issue that could prevent contact names from appearing in the Messages app and notifications
Fixes an issue that could impact ability to respond to notifications
Resolves an issue where the Stocks complication may not update on the watch face
Fixes an issue that may prevent the Activity rings from displaying on the Activity watch faces
Fixes an issue that prevented the dials on an analog watch face from appearing after changing the temperature unit in the Weather app
Resolves an issue that could cause the Maps app to stay launched after navigation has ended
Resolves an issue where the incorrect date could be displayed in the Calendar app month view
January 23, 2017; 17 months ago (2017-01-23)
General performance and stability improvements
March 27, 2017; 15 months ago (2017-03-27)
Theater mode to temporarily disable the raise to wake feature
SiriKit to allow third party apps access to Siri
Find My iPhone now supports Location and Play Sound for AirPods.
Initial Release on Apple Watch Series 3 (Dual-Core)
New Siri face that intelligently updates information based on time of day, location, and daily routines
New animated Toy Story faces featuring Woody, Buzz Lightyear, Jessie and more
New Kaleidoscope face that turns static images into symmetrical, intertwining patterns
New complications for Siri, News, Heart Rate, Now Playing, and Messages
Intelligent and personalized notifications to help you close your Activity rings each day
Monthly challenges based on the previous month's activity levels
New full screen animations to celebrate important milestones including earning an achievement and closing your rings
Replies to activity sharing notifications now include workout metrics
Redesigned app for quick starts and helpful workout type graphics
New High Intensity Interval Training (HIIT) workout with custom motion and heart rate algorithms for more accurate calorie tracking
Support for multiple workout types in one workout session
Auto sets for Pool Swim workouts with distance for each stroke type and pace for each set, automatically adjusted for rest time
Ability to automatically start a synced music playlist when you start a workout on Apple Watch Series 1 and later
Access to music controls directly in the Workout app during a workout session
Option for Do Not Disturb to be automatically turned on during workouts
New visual graph showing all-day heart rate
New heart rate measurements and visual graphs for resting rate (Apple Watch Series 1 and later), walking average, workout average and high, recovery time, and sessions in the Breathe app
Option to be notified if your heart rate rises above a specified threshold while you appeared to be inactive for a 10-minute period (Apple Watch Series 1 and later)
Current and historical details of heart rate data in the Health app on iPhone, including new Heart Rate Variability (HRV) and VO2 Max data types
Redesigned app for easy scrolling through album art
Ability to sync multiple playlists for local playback with bluetooth headphones
Automatically sync curated playlists from Apple Music including Heavy Rotation, My New Music Mix, and My Favorites Mix
Other features and improvements
News app with summaries of Top Stories and save for later to read on iPhone
Flashlight and Safety Light in Control Center
Vertical scrolling through recently used apps in the Dock
App home screen available in an alphabetical list view
Mail compose and swipe gestures
Dialer pad in the Phone app
Conflicts displayed in Calendar invites
Scribble support for German
Sub-minute and repeating timers
Suggested and recent locations in Maps
Contacts and locations in smart replies
October 4, 2017; 9 months ago (2017-10-04)
Apple Watch Series 3 (GPS + Cellular) only
Fixes issues that were causing Apple Watch to join unauthenticated (captive) Wi-Fi networks, such as those often found in public places like coffee shops and hotels, which direct the user to a web page before the network can be accessed.
October 31, 2017; 8 months ago (2017-10-31)
Over 70 new emoji characters including new food types, animals, mythical creatures, clothing options, more expressive smiley faces, gender-neutral characters and more
Stream music on Apple Watch Series 3 with Apple Music or iCloud Music Library
Listen to live radio on Beats 1, custom stations and expert-curated stations with the new Radio app on Apple Watch Series 3
Use Siri to find, discover and play songs, playlists or albums
Sync fitness data with GymKit-enabled treadmills, ellipticals, stair steppers and indoor bikes for more accurate distance, pace and energy burn metrics
Ability to disconnect from a Wi-Fi network in Control Center for Apple Watch Series 3 (GPS + Cellular)
Fixes an issue for Apple Watch Series 1 and later where Heart Rate notifications were delivered when the feature was not enabled
Fixes an issue where some users did not receive Stand Reminders
Resolves an issue where the current stand hour indicator did not appear for some users
Resolves an issue that caused haptics to not be delivered for silent alarms
Addresses an issue that prevented Apple Watch (1st generation) from charging for some users
Resolves an issue where the Sunrise and Sunset complication would sometimes not appear
Restores Mandarin as the default dictation language for China
December 5, 2017; 7 months ago (2017-12-05)
Send, request, and receive money from friends and family with Apple Pay Cash in Messages or by asking Siri (US only)
Adds support for HomeKit sprinklers and faucets in Home
Adds support for a new workout type for third-party apps to track distance, average speed, number of runs, and elevation descended for downhill snow sports with Apple Watch Series 3
Resolves an issue where Apple Watch would sometimes restart when asking Siri about the weather
Fixes an issue where scrolling was disabled in Heart Rate for some users
Resolves an issue that prevented simultaneous timers or alarms from being dismissed independently
January 23, 2018; 5 months ago (2018-01-23)
This update includes improvements and bug fixes.
February 19, 2018; 4 months ago (2018-02-19)
Fixes an issue where using certain character sequences could cause apps to crash.
March 29, 2018; 3 months ago (2018-03-29)
Control volume and playback on HomePod from your Apple Watch
Restores ability to control music on iPhone
Use any orientation for Nightstand charging mode
Siri watch face now shows progress towards closing Activity rings and when new songs are added to Apple Music mixes
Resolves an issue where Activity achievements were incorrectly awarded for some users
Fixes an issue where Siri music commands were not working for some audio devices
May 29, 2018; 49 days ago (2018-05-29)
Fixes an issue which caused Apple Watch to sometimes remain at the Apple Logo during startup for some users.
Added Pride Watch Face to coding, became usable during WWDC2018 on 6/4/2018
July 9, 2018; 8 days ago (2018-07-09)
Final release supported on Apple Watch (1st generation)