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HomeiOS DevelopmentExperimenting with Dwell Actions – Ole Begemann

Experimenting with Dwell Actions – Ole Begemann


iOS 16 beta 4 is the primary SDK launch that helps Dwell Actions. A Dwell Exercise is a widget-like view an app can place in your lock display and replace in actual time. Examples the place this may be helpful embrace reside sports activities scores or practice departure occasions.

These are my notes on taking part in with the API and implementing my first Dwell Exercise.

A motorbike pc in your lock display

My Dwell Exercise is a show for a motorbike pc that I’ve been creating with a bunch a associates. Right here’s a video of it in motion:

And right here with simulated knowledge:

I haven’t talked a lot about our bike pc challenge publicly but; that may hopefully change sometime. Briefly, a bunch of associates and I designed somewhat field that connects to your bike’s hub dynamo, measures velocity and distance, and sends the information by way of Bluetooth to an iOS app. The app information all of your rides and may act as a reside speedometer when mounted in your bike’s handlebar. It’s this final function that I needed to duplicate within the Dwell Exercise.

Observe Apple’s information

Including a Dwell Exercise to the app wasn’t laborious. I discovered Apple’s information Displaying reside knowledge on the Lock Display with Dwell Actions simple to comply with and fairly complete.

No express person approval

iOS doesn’t ask the person for approval when an app needs to indicate a Dwell Exercise. I discovered this odd because it appears to ask builders to abuse the function, however possibly it’s OK due to the foreground requirement (see beneath). Plus, customers can disallow Dwell Actions on a per-app foundation in Settings.

Customers can dismiss an energetic Dwell Exercise from the lock display by swiping (like a notification).

Most apps will most likely have to ask the person for notification permissions to replace their Dwell Actions.

The app should be within the foreground to start out an exercise

To start out a Dwell Exercise, an app should be open within the foreground. This isn’t superb for the bike pc as a result of the speedometer can’t seem magically on the lock display when the person begins using (though iOS wakes up the app within the background at this level to ship the Bluetooth occasions from the bike). The person has to open the app manually a minimum of as soon as.

Then again, this limitation will not be a difficulty for many use instances and can most likely reduce down on spamming/abuse considerably.

The app should hold operating within the background to replace the exercise (or use push notifications)

So long as the app retains operating (within the foreground or background), it may replace the Dwell Exercise as typically because it needs (I feel). That is superb for the bike pc because the app retains operating within the background processing Bluetooth occasions whereas the bike is in movement. I assume the identical applies to different apps that may stay alive within the background, similar to audio gamers or navigation apps doing steady location monitoring.

Updating the Dwell Exercise as soon as per second was no downside in my testing, and I didn’t expertise any charge limiting.

Most apps get suspended within the background, nonetheless. They have to use push notifications to replace their Dwell Exercise (or background duties or another mechanism to have the system wake you up). Apple launched a brand new form of push notification that’s delivered on to the Dwell Exercise, bypassing the app altogether. I haven’t performed with push notification updates, so I don’t know the advantages of utilizing this methodology over sending a silent push notification to wake the app and updating the Dwell Exercise from there. Most likely much less aggressive charge limiting?

Lock display colour matching

I haven’t discovered a great way to match my Dwell Exercise’s colours to the present system colours on the lock display. By default, textual content in a Dwell Exercise is black in gentle mode, whereas the built-in lock display themes appear to favor white or different gentle textual content colours. If there’s an API or setting worth that enables apps to match the colour type of the present lock display, I haven’t discovered it. I experimented with numerous foreground types, similar to supplies, with out success.

I ended up hardcoding the foreground colour, however I’m not happy with the end result. Relying on the person’s lock display theme, the Dwell Exercise can look misplaced.



The default textual content colour of a Dwell Exercise in gentle mode is black. This doesn’t match most lock display themes.

Animations can’t be disabled

Apple’s information clearly states that builders have little management over animations in a Dwell Exercise:

Animate content material updates

Whenever you outline the person interface of your Dwell Exercise, the system ignores any animation modifiers — for instance, withAnimation(_:_:) and animation(_:worth:) — and makes use of the system’s animation timing as an alternative. Nevertheless, the system performs some animation when the dynamic content material of the Dwell Exercise modifications. Textual content views animate content material modifications with blurred content material transitions, and the system animates content material transitions for photos and SF Symbols. In case you add or take away views from the person interface based mostly on content material or state modifications, views fade out and in. Use the next view transitions to configure these built-in transitions: opacity, transfer(edge:), slide, push(from:), or combos of them. Moreover, request animations for timer textual content with numericText(countsDown:).

It makes complete sense to me that Apple doesn’t need builders to go loopy with animations on the lock display, and maybe having full management over animations additionally makes it simpler for Apple to combine Dwell Actions into the always-on show that’s most likely approaching the following iPhone.

What shocked me is that I couldn’t discover a approach to disable the textual content change animations altogether. I discover the blurred textual content transitions for the massive velocity worth fairly distracting and I feel this label would look higher with none animations. However no mixture of .animation(nil), .contentTransition(.identification), and .transition(.identification) would do that.

A Dwell Exercise could be very very similar to a widget: the UI should reside in your app’s widget extension. You begin the Dwell Exercise with code that runs in your app, although. Each targets (the app and the widget extension) want entry to a typical knowledge sort that represents the information the widget shows. It is best to have a 3rd goal (a framework or SwiftPM package deal) that incorporates such shared varieties and APIs and that the downstream targets import.

Availability annotations

WidgetBundle apparently doesn’t assist widgets with completely different minimal deployment targets. In case your widget extension has a deployment goal of iOS 14 or 15 for an current widget and also you now need to add a Dwell Exercise, I’d anticipate your widget bundle to appear like this:

@important
struct MyWidgets: WidgetBundle {
  var physique: some Widget {
    MyNormalWidget()
    // Error: Closure containing management stream assertion can't
    // be used with end result builder 'WidgetBundleBuilder'
    if #out there(iOSApplicationExtension 16.0, *) {
      MyLiveActivityWidget()
    }
  }
}

However this doesn’t compile as a result of the end result builder sort utilized by WidgetBundle doesn’t assist conditionals. I hope Apple fixes this.

This wasn’t an issue for me as a result of our app didn’t have any widgets till now, so I simply set the deployment goal of the widget extension to iOS 16.0. In case you have current widgets and may’t require iOS 16 but, a workaround is so as to add a second widget extension goal only for the Dwell Exercise. I haven’t tried this, however WidgetKit explicitly helps having a number of widget extensions, so it ought to work:

Usually, you embrace all of your widgets in a single widget extension, though your app can comprise a number of extensions.

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