How-to guides

Find a procedure for a specific app development task.

• Troubleshooting

  Diagnose setup, build, device, signing, and launch problems in a Day project.

• Navigation

  Sidebar and tab selection, push/pop stacks, routes, and deep links, with native containers underneath.

• Localization

  Organize Fluent catalogs by app, crate, or source module; use generated Rust accessors; add languages and check translations.

• Accessibility

  Accessible labels and roles, platform limitations, and checks for the native accessibility tree.

• Testing with dayscript

  The YAML automation language that drives a running Day app: steps, assertions, screenshots, and how it works.

• Resources, images, fonts & icons

  How resource/assets, images, vectors, fonts, and icons travel from your project into each platform's native resource system, and how to read them back.

• Logging

  Day emits through the `log` facade: levels, per-platform sinks, DAY_LOG, and how to install env_logger, tracing, or your own logger.

• Tweaks

  Configuring the native widget behind a built-in piece, per toolkit and case by case, without writing a custom piece.

• Embed SwiftUI views

  Ship a SwiftPM package inside your app and call its SwiftUI views from Rust as generated, typed constructors — on macOS and iOS.

• Local notifications

  Immediate and scheduled notifications, permissions, and tap handling.

• Local storage

  Persistent settings and app-private files on native and web targets.

• HTTP requests

  Asynchronous HTTP requests, response handling, and cancellation.

• Permissions

  Build-time permission declarations and runtime access requests.

• Build flavors

  Ship one source tree as several apps — a paid build, a white-label build, a demo — with Day-<name>.toml and day build --flavor.

• Menus, toolbars, and windows

  Install a native menu bar with standard roles and shortcuts, put commands in the window's toolbar, and open secondary windows, including the standard Settings window, from your app.

• Packaging & distribution

  Build desktop installers and mobile app packages, configure signing, and inspect distribution status.

• GitHub Actions

  Build and test a Day app in CI, publish release packages, and deploy its website with the shared dayapp workflow.

• App websites

  Set up a localized app website, customize daysite or own its Astro pages, and publish with Day's GitHub Actions workflow and an optional custom domain.

• App icons and interface icons

  App-icon generation, interface SVGs, and platform rendering limits.

• App Store Submissions

  Prepare store listings, configure signing credentials, and submit iOS, Mac App Store and Android releases through GitHub Actions.

• Reusable commands

  Share an operation, its title, and availability across buttons, menus, and toolbars.

• Crash reporting

  Local crash reports and user-approved delivery by HTTP, GitHub, or email.

• Opening documents

  Register file types, import files, and handle Finder, file-manager and installed web app activations.

• App icons

  Build platform icon families from one master SVG, create seeded source icons, and check for drift.

• HarmonyOS backend

  The ArkUI backend in depth: the C node API, the ArkTS shim, hvigor packaging, and emulator workflows.

• macOS App Sandbox

  Configure signed sandboxed AppKit builds, file access, and persistent security-scoped bookmarks.

• Store listings

  store/storefront.toml: the App Store and Google Play listing, submission info, text per locale and screenshots in one file, validated by day lint and packaged by the release pipeline.

• VS Code extension

  The Day extension: the target cockpit, MCP tools for agent mode, and Day.toml schema wiring.

• Web backend

  The web-dom backend: Rust compiled to WebAssembly driving real DOM elements, the shim, and the launch server.

• WinUI 3 (windows-winui)

  The windows-winui target: the XAML backend built against WinUI 3 and the Windows App SDK.