Home > Articles > Mobile Application Development & Programming

Creating Custom Apple Watch Complications, Part 1

Wei-Meng Lee, author of Learning WatchKit Programming: A Hands-On Guide to Creating Apple Watch Applications, continues his exploration of what's new for developers in watchOS 2. This time, he shows how to create complications for the watch faces on the Apple Watch.
Like this article? We recommend

Complications on watches have always been one of the key differentiators of expensive timepieces. Put simply, a complication is a function on a timepiece that does more than just tell the time—alarms, tachymeters, chronographs, calendars, and so on. Figure 1 shows an example of complications on a watch.

Figure 1 Gallet MultiChron Navigator (1943) with three complications: 45-minute recording chronograph, crown-controlled synchronizable second hand, and direction-finding 24-hour hand (Source: Wikipedia.)

Apple has aptly implemented complications on the various faces of its Apple Watch—complications that display data from applications such as Activity, Calendar, and so on. In watchOS 2, third-party apps can also display data in watch face complications. This article walks you through the process of creating an application that displays data on the Apple Watch complications.

Types of Complications

Complications on the Apple Watch are classified into the following families:

  • Modular Small (see Figure 2)—a medium-sized square area used in digital interfaces
  • Modular Large (see Figure 3)—a large rectangular area used in digital interfaces
  • Circular Small (see Figure 4)—a small circular area used in analog interfaces
  • Utilitarian Small (see Figure 5)—a small square or rectangular area used in analog interfaces
  • Utilitarian Large (see Figure 6)—a small rectangular area that spans the width of the screen

Note that the first two families (Modular Small and Modular Large) are used in digital watch faces, and the rest are used in analog watch faces.

Figure 2 Modular Small complication.

Figure 3 Modular Large complication.

Figure 4 Circular Small complication.

Figure 5 Utilitarian Small complication.

Figure 6 Utilitarian Large complication.

The available complication types depend on the specific watch face. Some watch faces support multiple complication families; others don't support complications at all.

The ClockKit Framework manages the display of all complications data.

Creating the Project

Now that you have a better idea of the types of complications on the Apple Watch, let's create a project and see how a complication works. For this example, we'll create a project that displays the timing of the various movies played in a cinema.

  1. Using Xcode 7, create an iOS App with WatchKit App project (see Figure 7).
  2. Figure 7 Creating a WatchKit App project.

  3. Name the project Movies. Turn off the Include Notification Scene option and turn on the Include Complication option (see Figure 8).
  4. Figure 8 Check the Include Complication option to support complications in your application.

When the project is created, notice that a file named ComplicationController.swift appears under the Movies WatchKit Extension (see Figure 9).

Figure 9 The ComplicationController.swift file is used for displaying complication data.

The ComplicationController.swift file contains the definition for the ComplicationController class, which implements the CLKComplicationDataSource protocol. This protocol allows you to implement all the methods that pass your complication data to the ClockKit Framework. Specifically, you need to implement the following methods in the CLKComplicationDataSource protocol:

  • getSupportedTimeTravelDirectionsForComplication:withHandler: is called to retrieve the time travel directions that your complication supports.
  • getTimelineStartDateForComplication:withHandler: is called to retrieve the earliest date that your complication is ready to supply data.
  • getTimelineEndDateForComplication:withHandler: is called to retrieve the latest date that your complication is ready to supply data.
  • getPrivacyBehaviorForComplication:withHandler: returns the privacy behavior for the specified complication style.
  • getCurrentTimelineEntryForComplication:withHandler: is called to display the timeline entry you want to display now.
  • getTimelineEntriesForComplication:beforeDate:limit:withHandler: is called to retrieve past timeline entries for the complication.
  • getTimelineEntriesForComplication:afterDate:limit:withHandler: is called to retrieve future timeline entries for the complication.
  • getNextRequestedUpdateDateWithHandler: is called to get the next update time for the complication.
  • getPlaceholderTemplateForComplication:withHandler: returns a static template to display in the selection screen for the complication.

The ClockKit Framework executes all the methods in the ComplicationController class in the background before the watch face displays your data in the complications. This execution model allows the user to see the data displayed in the complications instantly when the watch face lights up (such as when the user raises his wrist). This capability also gives the ComplicationController class sufficient time to fetch the data to be displayed in the complications.

In the Project Navigator, selecting the Movies WatchKit Extension target shows all the complication families supported by the app (see Figure 10). Remove the checks from any features you don't want your app to support.

Figure 10 Select which complication families your application will support.

Creating the Placeholder Template

Let's implement the first method in the ComplicationController class—getPlaceholderTemplateForComplication:withHandler:. This method returns a static template to display in the selection screen for your complication.

  1. Add the following statements in bold to the ComplicationController.swift file:
  2. import ClockKit
    //---multipliers to convert to seconds---
    let HOUR: NSTimeInterval = 60 * 60
    let MINUTE: NSTimeInterval = 60
        func getPlaceholderTemplateForComplication(
            complication: CLKComplication,
            withHandler handler: (CLKComplicationTemplate?) -> Void) {
            // This method will be called once per supported complication, and
            // the results will be cached
            // handler(nil)
            var template: CLKComplicationTemplate?
            switch complication.family {
            case .ModularSmall:
                let modularSmallTemplate =
                modularSmallTemplate.textProvider =
                    CLKSimpleTextProvider(text: "R")
                modularSmallTemplate.fillFraction = 0.75
                modularSmallTemplate.ringStyle = CLKComplicationRingStyle.Closed
                template = modularSmallTemplate
            case .ModularLarge:
                let modularLargeTemplate =
                modularLargeTemplate.headerTextProvider =
                    CLKTimeIntervalTextProvider(startDate: NSDate(),
                        endDate: NSDate(timeIntervalSinceNow: 1.5 * HOUR))
                modularLargeTemplate.body1TextProvider =
                    CLKSimpleTextProvider(text: "Movie Name",
                        shortText: "Movie")
                modularLargeTemplate.body2TextProvider =
                    CLKSimpleTextProvider(text: "Running Time",
                        shortText: "Time")
                template = modularLargeTemplate
            case .UtilitarianSmall:
                template = nil
            case .UtilitarianLarge:
                template = nil
            case .CircularSmall:
                template = nil
  3. In this method, you first check which type of complications you want to support by examining the CLKComplication object that is passed in. (For simplicity, this article supports both the Modular Small and Modular Large complications.) Once you've determined the type of complications you want to support, you need to use one of the many templates available for each complication:
    • For the Modular Small complication, I'll use the CLKComplicationTemplateModularSmallRingText class. This class displays a single text string encircled by a configurable progress ring.
    • For the Modular Large complication, I'll use the CLKComplicationTemplateModularLargeStandardBody class. This class displays a header row with two lines of text.

    In addition to the CLKSimpleTextProvider class, you use the CLKTimeIntervalTextProvider class to display a range of time. This class is smart enough to display the string efficiently, taking into consideration the space available for display and the user's region and locale.

  4. To test the application, select the Complication—Movies WatchKit App scheme at the top of the Xcode window and then select iPhone 6 + Apple Watch—38mm (see Figure 11). This step deploys the iOS app and the WatchKit app to the iPhone 6 and Apple Watch Simulator, respectively.
  5. Figure 11 Selecting the complication scheme in Xcode.

  6. On the Apple Watch Simulator, press Command-Shift-2 to simulate a deep press. Then click on the watch face. Notice that you can now change the watch face, as shown in Figure 12.
  7. Figure 12 Changing the watch face.

  8. Press Command-Shift-1 to simulate a shallow press. Then swipe the watch face to the left. You should now see the Modular watch face, as shown in Figure 13.
  9. Figure 13 Changing to the Modular watch face.

  10. Click Customize. Notice that you can customize the watch face (see Figure 14).
  11. Figure 14 Customizing the watch face.

  12. Click and swipe to the left. You'll see the watch face as shown in Figure 15.
  13. Figure 15 Changing to the next customizable screen of the watch face.

  14. Select the complication named CALENDAR and move the scroll wheel on your mouse. The complication will change. Move the scroll wheel until you reach the MOVIES WATCHKIT APP item (the name of your app), as shown in Figure 16.
  15. Figure 16 Changing the complication to your project.

  16. Select the ACTIVITY complication in the middle of the bottom row (see Figure 17).
  17. Figure 17 Selecting the next complication to change.

  18. Move the scroll wheel until you see MOVIES WATCHKIT APP (see Figure 18).
  19. Figure 18 Changing the complication for the project.

  20. Press Command-Shift-2 and then click on the watch face (see Figure 19).
  21. Figure 19 Deep press the watch face to exit the customization mode.

  22. Press Command-Shift-1 and click on the watch face. The watch face should now look like Figure 20.
  23. Figure 20 The watch face displays complication data from your app.

The first complication displays the following data:

  • A header showing a time interval of 1.5 hours, starting from the time when the complication was added
  • Two lines of text—Movie Name and Running Time

The second complication displays a three-quarter circle with the letter R inside it.

Setting Privacy Behavior

The next method you need to implement is the getPrivacyBehaviorForComplication:withHandler: method, which returns the privacy behavior for the specified complication style. If you want the complication data to display even when the watch is locked, use the ShowOnLockScreen enumeration:

func getPrivacyBehaviorForComplication(
    complication: CLKComplication,
    withHandler handler: (CLKComplicationPrivacyBehavior) -> Void) {


In this article, you have seen what a complication is and how to implement it in your Apple Watch application. In the next article in this series, you will modify your application to display some real data and implement Time Travel—a feature in watchOS 2 that allows users to use the Digital Crown to scroll through time-sensitive complication data on the various watch faces.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020