Architecture: screenshots
How kinhin mobile init sets up store screenshots, what the lane does on each platform, and how the screenshots leave the VM. This page is a companion to the architecture overview; the setup guide is Store screenshots with fastlane.
Scope
Screenshots are a fastlane job, not a kinhin runtime. kinhin scaffolds the files and runs the workflow on a runner, and fastlane does the capture, framing and upload. kinhin never edits your Xcode project or your Gradle files, because a script that edits them is easy to break. Those steps are manual and documented in the setup guide.
Scaffolding
Sources/KinhinKit/Mobile/ holds the templates and scaffold logic. kinhin mobile init writes three kinds of file:
| Written by kinhin | Where | Purpose |
|---|---|---|
| Lane | The project's fastlane folder (screenshots lane) | Calls snapshot on iOS or screengrab on Android |
| Settings | fastlane/Snapfile, fastlane/Framefile.json, fastlane/Screengrabfile | Devices, languages, frames, locales |
| Sample UI tests | UITests/ (iOS), app/src/androidTest/java/screenshots/ (Android) | The screens fastlane photographs |
You still add the UI test target to the Xcode project, and the instrumented test source set to Gradle.
Capture on each platform
flowchart LR
lane["fastlane screenshots"] --> ios["iOS: snapshot"]
lane --> android["Android: screengrab"]
ios --> sim["Simulator runs UI tests<br>one run per device and language"]
android --> emu["Emulator or device runs instrumented tests<br>one run per locale"]
sim --> png["PNGs per locale<br>fastlane/screenshots or metadata/android"]
emu --> png
png --> frame{"FRAME_SCREENSHOTS = 1?"}
frame -- yes --> frameit["frameit adds device frames"]
frame -- no --> out["Screenshot folders"]
frameit --> out
out --> up{"UPLOAD_SCREENSHOTS = 1?"}
up -- yes --> store["Upload to App Store Connect or Google Play"]
up -- no --> keep["Kept on disk"]
The lane exits 0 only when at least one PNG exists, so an empty run fails loudly rather than passing silently. Upload is off unless you turn it on, and framing is optional.
Each platform's settings map to fastlane's own options. Variables set in the CI workflow choose the devices, languages, locales and frame and upload toggles. The full list is in the settings table.
CI flow
The CI job runs the lane on the macOS runner, then uploads the screenshots as a workflow artifact. The VM is deleted when the job ends, so the artifact is the only copy that survives.
flowchart LR
job["mobile job on a macOS runner"] --> run["Run lane<br>iOS and Android"]
run --> artifact["Upload artifact<br>ios-screenshots or android-screenshots, kept 14 days"]
artifact --> reader["Anyone who can read the run"]
run -. "upload toggle" .-> stores["App Store Connect or Google Play"]
Upload the artifact even when the lane fails, so the partial screenshots are available for debugging. Because anyone who can read the run can open the artifact, the sample screens use test accounts and fake data.
The Android job runs on the same macOS runner as iOS. screengrab needs an emulator or device on that runner, which the runner image must provide. The setup has not been verified on a runner.
From screenshots to a video
Screenshots can feed a launch video. A device scene in a project's video file takes PNG paths as props.screens and shows them as a cross-fading slideshow. The mobile-capture job in the video workflow captures them for a look that sets screens.
flowchart LR
shots["Screenshot PNGs"] --> scene["device scene<br>props.screens"]
scene --> build["kinhin video build"]
build --> video["Launch video"]
See making a video and CI video for the details.