Experimenting with Reside Actions – Ole Begemann

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iOS 16 beta 4 is the primary SDK launch that helps Reside Actions. A Reside 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 embody dwell sports activities scores or prepare departure instances.

These are my notes on taking part in with the API and implementing my first Reside Exercise (which has a barely atypical use case, however that shouldn’t matter).

A motorcycle laptop in your lock display

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

And right here with simulated information within the simulator:

I haven’t talked a lot about our bike laptop undertaking publicly but; that may hopefully change sometime. Briefly, a gaggle of associates and I designed a little bit field that connects to your bike’s hub dynamo, measures pace and distance, and sends the information by way of Bluetooth to an iOS app. The app data all of your rides and may act as a dwell speedometer when mounted in your bike’s handlebar. It’s this final function that I needed to copy within the Reside Exercise.

Comply with Apple’s information

Including a Reside Exercise to the app wasn’t onerous. I discovered Apple’s information Displaying dwell information on the Lock Display with Reside Actions simple to observe and fairly complete.

No specific consumer approval

iOS doesn’t ask the consumer for approval when an app needs to point out a Reside Exercise. I discovered this odd because it appears to ask builders to abuse the function, however perhaps it’s OK due to the foreground requirement (see under). Customers can dismiss an energetic Reside Exercise from the lock display by swiping (like a notification).

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

The app have to be within the foreground to begin an exercise

To start out a Reside Exercise, an app have to be open within the foreground. This isn’t perfect for the bike laptop as a result of the speedometer can’t seem magically on the lock display when the consumer begins using (despite the fact that iOS wakes up the app within the background at this level to ship the Bluetooth occasions from the bike). The consumer has to open the app manually not less than as soon as.

Alternatively, this limitation might not be a difficulty for many use circumstances and can most likely lower down on spamming/abuse considerably.

The app should preserve 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 will probably replace the Reside Exercise with a single technique name. That is perfect for the bike laptop 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 Reside Exercise as soon as per second was no drawback in my testing, and I didn’t expertise any fee limiting.

Most apps get suspended within the background; they need to use push notifications to replace their Reside 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 Reside 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 Reside Exercise from there. Most likely much less aggressive fee limiting?

Lock display coloration matching

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

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


The default textual content coloration of a Reside Exercise in mild 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 Reside Exercise:

Animate content material updates

While you outline the consumer interface of your Reside 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 Reside Exercise adjustments. Textual content views animate content material adjustments with blurred content material transitions, and the system animates content material transitions for photos and SF Symbols. When you add or take away views from the consumer interface primarily based on content material or state adjustments, 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 Reside Actions into the always-on show that’s most likely approaching the following iPhone.

What shocked me is that I couldn’t discover a strategy to disable the textual content change animations altogether. I discover the blurred textual content transitions for the massive 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 Reside Exercise could be very very similar to a widget: the UI should dwell in your app’s widget extension. You begin the Reside Exercise with code that runs in your app, although. Each targets (the app and the widget extension) want entry to a standard information kind that represents the information the widget shows. You need to have a 3rd goal (a framework or SwiftPM bundle) that accommodates such shared sorts and APIs and that the downstream targets import.

Availability annotations

WidgetBundle apparently doesn’t assist widgets with totally different minimal deployment targets. In case your widget extension has a deployment goal of iOS 14 or 15 for an present widget and also you now wish to add a Reside Exercise, I’d count on your widget bundle to appear to be this:

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

However this doesn’t compile as a result of the outcome builder kind 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. If in case you have present widgets and may’t require iOS 16 but, a workaround is so as to add a second widget extension goal only for the Reside Exercise. I haven’t tried this, however WidgetKit explicitly helps having a number of widget extensions[^1], so it ought to work:

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

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