Some issues and questions regarding the use of the BGContinuedProcessingTask API

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Hi, I have been recently debugging the BGContinuedProcessingTask API and encountered some of the following issues. I hope you can provide some answers: First, let me explain my understanding of this API. I believe its purpose is to allow an app to trigger tasks that can be represented with progress indicators and require a certain amount of time to complete. After entering the background, these tasks can continue to be completed through the BGContinuedProcessingTask, preventing the system from terminating them before they are finished.

In the launchHandler of the registration process, we only need to do a few things:

Determine whether the actual business processing is still ongoing.
Update the progress, title, and subtitle.
Handle the expirationHandler.
Set the task as completed.

Here are some issues I encountered during my debugging process:

After I called register and submit, the BGContinuedProcessingTask could not be triggered. The return values from my API calls were all normal.

I tried different device models, and some could trigger the task normally, such as the 15 Pro Max and 12 Pro Max. However, there were also some models, such as the 17 Pro, 15 Pro, and 15, that could not trigger the task properly. Moreover, there was no additional error information to help locate the issue.

The background task failed unexpectedly, but my app was still running normally. As I mentioned above, my launchHandler only retrieves the actual business status and updates it.

If a background task fails unexpectedly while the app is still running normally, it can mislead users and degrade the user experience of the app.

Others have also mentioned the issue of inconsistent behavior on devices that do not support Dynamic Island. On devices that support Dynamic Island,

when a task is triggered in the foreground, the app does not immediately display a pop-up notification within the app. However, on devices that do not support Dynamic Island, the app directly displays a pop-up notification within the app, and this notification does not disappear when switching between different screens within the same app. The user needs to actively swipe up to dismiss it. I think this experience is too intrusive for users. I would like to know whether this will be maintained in the future or if there is a plan to fix it.

On devices that do not support Dynamic Island, using the beta version 26.1 of the system,

if the system is in dark mode but the app triggers a business interface in white, the pop-up notification will have the same color as the current page, making it difficult to read the content inside the pop-up.

Users can actively stop background tasks by using the stop button, or the system can also stop tasks automatically when resources are insufficient or when a task is abnormal.

However, according to the current API, all these actions are triggered through the expirationHandler. Currently, there is no way to distinguish whether the task was stopped by the user, by the system due to resource insufficiency, or due to an abnormal task. I would like to know whether there will be more information provided in the future to help distinguish these different scenarios.

I believe that the user experience issues mentioned in points 2 and 3 are the most important. Please help to answer the questions and concerns above. Thank you!

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Answer 1

Tommy_Yang OP

3d

I hope that some developers can answer the questions above. This interface was designed with the expectation of enhancing app experience. However, there are still some issues that need to be optimized.

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Answer 2

jwcarr OP

1d

I tried different device models, and some could trigger the task normally, such as the 15 Pro Max and 12 Pro Max. However, there were also some models, such as the 17 Pro, 15 Pro, and 15, that could not trigger the task properly. Moreover, there was no additional error information to help locate the issue.

I assume you're doing this on device and not the simulator, right? And did you check the Console logs to see if an error was reported there? (look for the dasd process)

I also just wanted to reiterate your other points about the BGContinuedProcessingTask API, in case someone from Apple is listening:

I agree that the experience on non-Dynamic Island devices is not great. The task notification banner thing is a obtrusive and redundant. My app already displays a progress bar, so displaying another progress indicator is redundant. Moreover, the banner obscures my app's UI and does not disappear automatically like normal notifications. This leaves the user uncertain if they can safely dismiss it, or if dismissing it will cancel the task. The banner is important to make the user aware that a background task is running, but it should only appear if/when the user backgrounds the app – that's when it becomes relevant.
Likewise, I've also noticed that the banner text is sometimes the wrong color – sometimes black text in dark mode, or white text in light mode. But I haven't been able to reproduce it consistently.
I totally agree that the API is missing a distinction between (1) the user has stopped the task and (2) the system wants to stop the task. In the case of (1), I want to completely cancel the task. In the case of (2), I want to put the task into a paused state until the user is ready to resume it. Ideally, the UI should inform the user that the task has been paused.

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