How to get video and screenshots of an iOS UI test failure

Set capture in your test plan

In Xcode 15, automatic XCTest screen recordings are on by default, in favor of screenshots. Two settings in a test plan’s configuration control them:

• Automatic Screen Capture controls screenshot capture and whether screenshots from passing tests are deleted.
• Preferred Capture Format picks video or screenshots.

You can also turn recordings off in the scheme’s Test action options.

For a screenshot at a moment you choose, attach one in the test. An attachment’s lifetime defaults to .deleteOnSuccess, so it survives only when the test fails. Set .keepAlways to keep it on a pass too:

let shot = XCTAttachment(screenshot: XCUIScreen.main.screenshot())shot.name = "Checkout total"shot.lifetime = .keepAlwaysadd(shot)

Export the failure from the result bundle

Run the tests with a result bundle, then export what’s attached to failures:

$ xcodebuild test -scheme YourApp \  -destination 'platform=iOS Simulator,name=iPhone 17 Pro' \  -resultBundlePath build/UITests.xcresult$ xcrun xcresulttool export attachments \  --path build/UITests.xcresult \  --output-path build/failures --only-failures

• xcodebuild exits with an error when the -resultBundlePath folder already exists. Delete the old bundle first.
• For an iPhone, use -destination 'platform=iOS,name=Test iPhone'.
• export attachments is available starting with Xcode 16. It writes each file and a manifest.json that lists, per test, the exportedFileName, isAssociatedWithFailure, deviceName and timestamp of each attachment.
• Upload build/failures as your CI job’s artifact.

On a simulator you can also record by hand while you reproduce a failure:

$ xcrun simctl io booted recordVideo --codec=h264 run.mov$ xcrun simctl io booted screenshot failure.png

recordVideo writes until you press ctrl+c, then finishes the file. Its default codec is HEVC.

Record every check with Mobster

A Mobster check is a YAML file of steps and expectations. mobster test runs every check in .mobster/checks. Add --video to record each run’s screen:

$ mobster test --video

The suite folder stands on its own, so every link works when you upload it as an artifact:

Every run also keeps its frames in .mobster/runs/<run_id>/frames/: the launch, one frame per step, the verdict frame, and the verdict frame with an accessibility overlay. The overlay outlines each asserted element in green when it passes and red when it fails. The numbers follow the check’s order.

How Mobster records:

• On a simulator, with xcrun simctl io <udid> recordVideo --codec=h264.
• On an iPhone on a USB cable, from WebDriverAgent’s video stream, encoded on your Mac to an H.264 MP4 590 pixels wide. Run it with mobster test --device "Test iPhone" --video. The one recorded iPhone run leaked file handles, and we haven’t tested it again since.

Put the failure on the pull request

mobster test pr runs the checks that cover the screens a branch changed. It writes pr-comment.md with each failure’s frame, and up to 6 captioned GIFs in pr/gifs/, failed checks first. On your own Mac runner, mobster ci run runs mobster test pr --video. The workflow that mobster ci init writes uploads .mobster/ci/ as the job’s artifact, with the frames, GIFs and videos. The comment links each one. --no-video turns the recordings off.

Keep your XCTest screenshots beside the checks

In the next release, you use mobster test --xctest to build your project with xcodebuild build-for-testing, run your XCTest targets on a simulator and read the .xcresult with xcresulttool. Your tests’ attachments land in xctest/attachments/, and each failed test in index.html links its screenshots. Mobster runs XCTest targets on simulators only.

What it costs

Mobster for Mac is free on simulators and iPhones. A launch-only check calls no model. A check with steps runs on your Claude or OpenAI API key until it passes once, then replays its recorded steps with no model call.