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 screen and replace in actual time. Examples the place this may be helpful embrace reside sports activities scores or practice departure instances.

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

A motorbike laptop in your lock display screen

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

And right here with simulated information:

I haven’t talked a lot about our bike laptop undertaking publicly but; that can hopefully change sometime. In brief, a bunch of mates and I designed just a little field that connects to your bike’s hub dynamo, measures pace and distance, and sends the info by way of Bluetooth to an iOS app. The app information all of your rides and also can act as a reside speedometer when mounted in your bike’s handlebar. It’s this final characteristic that I needed to copy within the Dwell Exercise.

Comply with Apple’s information

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

No express person approval

iOS doesn’t ask the person for approval when an app desires to indicate a Dwell Exercise. I discovered this odd because it appears to ask builders to abuse the characteristic, however perhaps 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 lively Dwell Exercise from the lock display screen by swiping (like a notification).

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

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

To start out a Dwell Exercise, an app have to be open within the foreground. This isn’t very best for the bike laptop as a result of the speedometer can’t seem magically on the lock display screen when the person begins driving (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 at the least as soon as.

Then again, this limitation is probably not a problem for many use circumstances and can most likely reduce down on spamming/abuse considerably.

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

So long as the app retains working (within the foreground or background), it may replace the Dwell Exercise as usually because it desires (I believe). That is very best for the bike laptop because the app retains working 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, comparable to audio gamers or navigation apps doing steady location monitoring.

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

Most apps get suspended within the background, nevertheless. 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 type 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 technique over sending a silent push notification to wake the app and updating the Dwell Exercise from there. Most likely much less aggressive price limiting?

Lock display screen coloration matching

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

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

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

Once 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. Should you add or take away views from the person interface primarily based 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 mixtures of them. Moreover, request animations for timer textual content with numericText(countsDown:).

It makes whole sense to me that Apple doesn’t need builders to go loopy with animations on the lock display screen, 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 subsequent iPhone.

What shocked me is that I couldn’t discover a option to disable the textual content change animations altogether. I discover the blurred textual content transitions for the big pace worth fairly distracting and I believe this label would look higher with none animations. However no mixture of .animation(nil), .contentTransition(.id), and .transition(.id) 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 standard information sort that represents the info the widget shows. You must have a 3rd goal (a framework or SwiftPM package deal) that incorporates such shared sorts and APIs and that the downstream targets import.

Availability annotations

WidgetBundle apparently doesn’t help 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 wish to add a Dwell Exercise, I’d anticipate your widget bundle to seem like this:

@primary
struct MyWidgets: WidgetBundle {
  var physique: some Widget {
    MyNormalWidget()
    // Error: Closure containing management move assertion can not
    // be used with outcome builder 'WidgetBundleBuilder'
    if #accessible(iOSApplicationExtension 16.0, *) {
      MyLiveActivityWidget()
    }
  }
}

However this doesn’t compile as a result of the outcome builder sort utilized by WidgetBundle doesn’t help availability circumstances. 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. If 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 include a number of extensions.