feat: setup background task from scratch on iOS

[szymonrybczak]

Explanation of Change

Warning

This Pull Request is rebased on top of the Upgrade to React Native 0.76 Pull Request because it's using a new type-safe way of creating EventEmitters available only in 0.76.

Adds an implementation of background task on iOS. This implemenation leverages BGTaskScheduler API, which is iOS specific API available from iOS 13 responsible for scheduling and executing background tasks. For our specific use case we're using BGProcessingTask which is designed for executing longer tasks e.g. syncing requests as in our case that can take longer.

From the more technical perspective it's a C++ TurboModule that was bootstrapped as a Local Library so it's linked inside package.json.

For now, we're scheduling new tasks in 15-minute intervals after the execution of the previous one.

How to test it?

To force execution of the background task can use Xcode debugger attached to physical iPhone device:

e -l objc -- (void)[[BGTaskScheduler sharedScheduler] _simulateLaunchForTaskWithIdentifier:@"com.bundle.id"]

Here's a video presenting this behaviour:

CleanShot.2024-12-10.at.11.59.35.mp4

Fixed Issues

$ #50140
PROPOSAL: #50140

Tests

• Verify that no errors appear in the JS console

Offline tests

QA Steps

1. Open the app on physical iPhone with Account A
2. Open the app on Web with Account B
3. With Account A activate the Flight mode and send some messages, for easier tracking send from 1 to 9, each on its one message
4. Move Account A’s app into background
5. Enable turn off the Flight mode
6. Watch the Account B, messages and any performed actions should show up

Note: take into account that could some time for the first time, this times will be improved and vary depending on the app usage on the device. We set the interval between tasks to 15 minutes but at the end of the day iOS decides when to execute it.

PR Author Checklist

• I linked the correct issue in the ### Fixed Issues section above
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
  • I added steps for the expected offline behavior in the Offline steps section
  • I added steps for Staging and/or Production testing in the QA steps section
  • I added steps to cover failure scenarios (i.e. verify an input displays the correct error message if the entered data is not correct)
  • I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
  • I tested this PR with a High Traffic account against the staging or production API to ensure there are no regressions (e.g. long loading states that impact usability).
• I included screenshots or videos for tests on all platforms
• I ran the tests on all platforms & verified they passed on:
  • Android: Native
  • Android: mWeb Chrome
  • iOS: Native
  • iOS: mWeb Safari
  • MacOS: Chrome / Safari
  • MacOS: Desktop
• I verified there are no console errors (if there's a console error not related to the PR, report it or open an issue for it to be fixed)
• I followed proper code patterns (see Reviewing the code)
  • I verified that any callback methods that were added or modified are named for what the method does and never what callback they handle (i.e. toggleReport and not onIconClick)
  • [ x I verified that the left part of a conditional rendering a React component is a boolean and NOT a string, e.g. myBool && <MyComponent />.
  • I verified that comments were added to code that is not self explanatory
  • I verified that any new or modified comments were clear, correct English, and explained "why" the code was doing something instead of only explaining "what" the code was doing.
  • I verified any copy / text shown in the product is localized by adding it to src/languages/* files and using the translation method
    • If any non-english text was added/modified, I verified the translation was requested/reviewed in #expensify-open-source and it was approved by an internal Expensify engineer. Link to Slack message:
  • I verified all numbers, amounts, dates and phone numbers shown in the product are using the localization methods
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  • I verified proper file naming conventions were followed for any new files or renamed files. All non-platform specific files are named after what they export and are not named "index.js". All platform-specific files are named for the platform the code supports as outlined in the README.
  • I verified the JSDocs style guidelines (in STYLE.md) were followed
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• I followed the guidelines as stated in the Review Guidelines
• I tested other components that can be impacted by my changes (i.e. if the PR modifies a shared library or component like Avatar, I verified the components using Avatar are working as expected)
• I verified all code is DRY (the PR doesn't include any logic written more than once, with the exception of tests)
• I verified any variables that can be defined as constants (ie. in CONST.js or at the top of the file that uses the constant) are defined as such
• I verified that if a function's arguments changed that all usages have also been updated correctly
• If any new file was added I verified that:
  • The file has a description of what it does and/or why is needed at the top of the file if the code is not self explanatory
• If a new CSS style is added I verified that:
  • A similar style doesn't already exist
  • The style can't be created with an existing StyleUtils function (i.e. StyleUtils.getBackgroundAndBorderStyle(theme.componentBG))
• If the PR modifies code that runs when editing or sending messages, I tested and verified there is no unexpected behavior for all supported markdown - URLs, single line code, code blocks, quotes, headings, bold, strikethrough, and italic.
• If the PR modifies a generic component, I tested and verified that those changes do not break usages of that component in the rest of the App (i.e. if a shared library or component like Avatar is modified, I verified that Avatar is working as expected in all cases)
• If the PR modifies a component related to any of the existing Storybook stories, I tested and verified all stories for that component are still working as expected.
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• If the PR modifies the UI (e.g. new buttons, new UI components, changing the padding/spacing/sizing, moving components, etc) or modifies the form input styles:
  • I verified that all the inputs inside a form are aligned with each other.
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• If a new page is added, I verified it's using the ScrollView component to make it scrollable when more elements are added to the page.
• If the main branch was merged into this PR after a review, I tested again and verified the outcome was still expected according to the Test steps.

Screenshots/Videos

Android: Native

Android: mWeb Chrome

iOS: Native

iOS: mWeb Safari

MacOS: Chrome / Safari

MacOS: Desktop

[melvin-bot]

@Pujan92 Please copy/paste the Reviewer Checklist from here into a new comment on this PR and complete it. If you have the K2 extension, you can simply click: [this button]

[szymonrybczak]

Q: which one should we specify here?

[melvin-bot]

Hey, I noticed you changed some webpack configuration files. This can break production builds. Did you remember to run a production build locally to verify they still work?

[github-actions]

🚧 @mountiny has triggered a test build. You can view the workflow run here.

[github-actions]

🚧 @mountiny has triggered a test build. You can view the workflow run here.

[github-actions]

🧪🧪 Use the links below to test this adhoc build on Android, iOS, Desktop, and Web. Happy testing! 🧪🧪

Android 🤖	iOS 🍎
https://ad-hoc-expensify-cash.s3.amazonaws.com/android/53834/index.html	❌ FAILED ❌
	The QR code can't be generated, because the iOS build failed
Desktop 💻	Web 🕸️
https://ad-hoc-expensify-cash.s3.amazonaws.com/desktop/53834/NewExpensify.dmg	https://53834.pr-testing.expensify.com

---

👀 View the workflow run that generated this build 👀

[github-actions]

🚧 @thienlnam has triggered a test build. You can view the workflow run here.

[github-actions]

🧪🧪 Use the links below to test this adhoc build on Android, iOS, Desktop, and Web. Happy testing! 🧪🧪

Android 🤖	iOS 🍎
https://ad-hoc-expensify-cash.s3.amazonaws.com/android/53834/index.html	❌ FAILED ❌
	The QR code can't be generated, because the iOS build failed
Desktop 💻	Web 🕸️
https://ad-hoc-expensify-cash.s3.amazonaws.com/desktop/53834/NewExpensify.dmg	https://53834.pr-testing.expensify.com

---

👀 View the workflow run that generated this build 👀

[github-actions]

🚧 @mountiny has triggered a test build. You can view the workflow run here.

[github-actions]

🧪🧪 Use the links below to test this adhoc build on Android, iOS, Desktop, and Web. Happy testing! 🧪🧪

Android 🤖	iOS 🍎
https://ad-hoc-expensify-cash.s3.amazonaws.com/android/53834/index.html	https://ad-hoc-expensify-cash.s3.amazonaws.com/ios/53834/index.html
Desktop 💻	Web 🕸️
https://ad-hoc-expensify-cash.s3.amazonaws.com/desktop/53834/NewExpensify.dmg	https://53834.pr-testing.expensify.com

---

👀 View the workflow run that generated this build 👀

[mountiny]

@mananjadhav any updates?

[mananjadhav]

Will be checking in next 10 mins. I did check this yesterday and the messages didn't arrive in like 5-8 mins. I couldn't check after that. But I'll be doing another test today.

[mananjadhav]

@szymonrybczak I tried to test this and it didn't work for me. I sent a message at 21:55 my time and it's 22:13 my time right now. No messages. I sent 10-13.

I tried different variations and I checked on two iPhones by the way - iPhone X and iPhone 16 plus.

ios-background-to-foreground.MP4

Before Foreground waiting for the app in background

After Foreground

[mananjadhav]

@szymonrybczak any updates on this one?

[szymonrybczak]

hey @mananjadhav, to answer your question and how it should work, so iOS is very strict regarding executing any kind of background tasks and 15 minutes which are used as earliest begin date are indicating first possible execution of the task.

As mentioned in the docs:

Setting the property indicates that the background task shouldn’t start any earlier than this date. However, the system doesn’t guarantee launching the task at the specified date, but only that it won’t begin sooner.

So actually we don't have any guarantee on when it will be executed, as other doc says:

The delay between the time you schedule a background task and when the system launches your app to run the task can be many hours.

To validate the implementations locally there's this guide. I followed steps from it and aded a video inside this PR description which presents that for specific identifier correct callback is being executed on JS side.

I spent a lot of time of trying to find a way to test it inside a Release build, searched a lot of native-only examples but there's no other way for BGTaskScheduler API.

To test how big impact does it have on app experience I'd propose sending analytics when the background task is executed, so we'll have a clear picture on the reliability of this solution and how often iOS decides to execute it.

[mananjadhav]

Thanks for the patience here @szymonrybczak. Checklist completed here. I am not sure what the Comment on native files changed means. @mountiny Can you help?

[melvin-bot]

We did not find an internal engineer to review this PR, trying to assign a random engineer to #50140 as well as to this PR... Please reach out for help on Slack if no one gets assigned!

[luacmartins]

NAB maybe we should leave a comment on why src/setup/backgroundTask/index.ts is empty so people don't delete it

[luacmartins]

One of the checks is failing:

Run gh pr comment 53834 --body \
  gh pr comment 53834 --body \
  ":warning: This PR is possibly changing native code. It may cause problems in Hybrid App. Please ask Hybrid App team to review those changes in the Slack open-source channel. The C+ can help you with that. :warning:"
  shell: /usr/bin/bash -e {0}
  env:
    GITHUB_TOKEN: ***
failed to run git: fatal: not a git repository (or any of the parent directories): .git

That's not a blocker to merge this PR.

[melvin-bot]

Congrats, that's your 5th PR merged! 🎉 Do you know about the ContributorPlus role? It's an opportunity to earn more in the Expensify Open Source community. Keep up the great work - thanks!

[melvin-bot]

@luacmartins looks like this was merged without a test passing. Please add a note explaining why this was done and remove the Emergency label if this is not an emergency.

[luacmartins]

See above

[OSBotify]

✋ This PR was not deployed to staging yet because QA is ongoing. It will be automatically deployed to staging after the next production release.

[github-actions]

🚀 Deployed to staging by https://github.com/luacmartins in version: 9.0.86-0 🚀

platform	result
🤖 android 🤖	success ✅
🖥 desktop 🖥	cancelled 🔪
🍎 iOS 🍎	success ✅
🕸 web 🕸	success ✅
🤖🔄 android HybridApp 🤖🔄	success ✅
🍎🔄 iOS HybridApp 🍎🔄	success ✅

[github-actions]

🚀 Deployed to staging by https://github.com/luacmartins in version: 9.0.86-0 🚀

platform	result
🤖 android 🤖	success ✅
🖥 desktop 🖥	success ✅
🍎 iOS 🍎	success ✅
🕸 web 🕸	success ✅
🤖🔄 android HybridApp 🤖🔄	success ✅
🍎🔄 iOS HybridApp 🍎🔄	success ✅

[szymonrybczak]

NAB maybe we should leave a comment on why src/setup/backgroundTask/index.ts is empty so people don't delete it

I've added it in Android PR: 7472c60

[luacmartins]

Thanks!

[github-actions]

🚀 Deployed to production by https://github.com/mountiny in version: 9.0.86-3 🚀

platform	result
🤖 android 🤖	true ❌
🖥 desktop 🖥	success ✅
🍎 iOS 🍎	success ✅
🕸 web 🕸	success ✅
🤖🔄 android HybridApp 🤖🔄	failure ❌
🍎🔄 iOS HybridApp 🍎🔄	success ✅

[arosiclair]

@szymonrybczak any reason we committed this file to the repo? Normally it's just a temporary file used in production builds.

[gedu]

I will take a look at this, probably remove it and add it into the .gitignore, thanks for caching this

[gedu]

Working on this in this PR: #56169

[arosiclair]

Thanks but I already got to it in this PR: #57058