iOS Development

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

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

A motorbike pc in your lock display screen

My Reside Exercise is a show for a motorcycle pc that I’ve been creating with a gaggle a mates. 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 can hopefully change sometime. In brief, a gaggle of mates and I designed slightly 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 data all of your rides and can even act as a stay 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 laborious. I discovered Apple’s information Displaying stay knowledge on the Lock Display with Reside Actions simple to comply with and fairly complete.

No specific consumer approval

iOS doesn’t ask the consumer for approval when an app needs to indicate 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 beneath). Plus, customers can disallow Reside Actions on a per-app foundation in Settings.

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

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

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

To start out a Reside Exercise, an app have to be open within the foreground. This isn’t excellent for the bike pc as a result of the speedometer can’t seem magically on the lock display screen 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.

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

The app should maintain 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 possibly replace the Reside Exercise as typically because it needs (I feel). That is excellent 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, reminiscent of 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 price limiting.

Most apps get suspended within the background, nonetheless. They have 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. In all probability much less aggressive price limiting?

Lock display screen shade matching

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

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


The lock screen of an iPhone running iOS 16. The system text (clock, date) is in a light, whitish color. The Live Activity at the bottom of the screen has black text.
The default textual content shade of a Reside Exercise in gentle mode is black. This doesn’t match most lock display screen 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

Once 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 a substitute. Nonetheless, the system performs some animation when the dynamic content material of the Reside 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 consumer 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 screen, 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 subsequent iPhone.

What stunned me is that I couldn’t discover a technique to disable the textual content change animations altogether. I discover the blurred textual content transitions for the massive pace 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 Reside Exercise could be very very like a widget: the UI should stay 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 typical knowledge sort that represents the info the widget shows. You must have a 3rd goal (a framework or SwiftPM bundle) that incorporates such shared sorts and APIs and that the downstream targets import.

Availability annotations

WidgetBundle apparently doesn’t help widgets with totally 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 Reside Exercise, I’d anticipate your widget bundle to seem like this:

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

However this doesn’t compile as a result of the outcome builder sort utilized by WidgetBundle doesn’t help 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 Reside Exercise. I haven’t tried this, however WidgetKit explicitly helps having a number of widget extensions, so it ought to work:

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

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