Kalvender

A simple macOS calendar widget: month view with ISO week numbers and public holidays — no events, no permissions, no network access.

Kalvender answers questions like "what weekday is the 24th?", "which week number is that?" and "how many nights is July 17–19?" — right on your desktop, without involving calendar accounts or events.

  ◀      July 2026      ▶
  wk  M   T   W   T   F   S   S
  27          1   2   3   4   5
  28  6   7   8   9  10  11  12
  29 13  14  15 (16) 17  18  19
  30 20  21  22  23  24  25  26
  31 27  28  29  30  31
      Thu 16 July · wk 29    ✕

Features

• Month view with today marked by a ring in the accent color.
• Week numbers per ISO 8601 (Monday first, "first Thursday" rule) — correct even across year boundaries, where Dec 29–31 can be week 1 and Jan 1–3 week 52/53.
• Step between months with ◀ / ▶. To jump back, a Today button appears in the bottom-left corner whenever you're on another month (tapping the month title does the same); the title also turns accent-colored as a reminder. Browsing resets automatically at midnight.
• Select a date or a range, hotel-booking style: tap a day to select it — the row below the calendar shows its weekday, week number and any holiday. Tap a later day to select the whole range (shows the number of days and nights). Tap ✕, or the start date again, to clear. Ranges may span month boundaries and persist until cleared.
• Public holidays for 13 countries: holidays and Sundays in red, de facto eves (Christmas Eve, Heiligabend, Nochebuena, Grundlovsdag, Midsummer Eve and friends) in orange.
• Two per-widget settings (right-click → Edit "Kalvender"):
  • Language: English (default), Svenska or Español — controls month names, weekday letters, date formats and labels ("wk"/"v."/"sem.").
  • Holidays: None (default), or Sweden, Denmark, Finland, Norway, France, Germany, Italy, Netherlands, Peru, Portugal, Spain, United Kingdom, United States. Independent of the language setting — Swedish with US holidays is a valid combination.
• Medium and large widget sizes, light/dark mode, and the system's tinted widget rendering modes.
• Multiple widgets can have different settings (e.g. one Swedish, one Spanish).

Installation

Requires macOS 15 or later, and Xcode 16 or later to build.

1. Open Kalvender.xcodeproj in Xcode.
2. Select your development team under Signing & Capabilities for both targets (Kalvender and KalvenderWidget). A free Apple ID is enough for local use.
3. Run the app once (⌘R) — this registers the widget with the system.
4. Right-click the desktop → Edit Widgets… → search for Kalvender and add it.

Or from the terminal:

xcodebuild -project Kalvender.xcodeproj -scheme Kalvender \
  -configuration Debug -derivedDataPath build/DerivedData build
cp -R build/DerivedData/Build/Products/Debug/Kalvender.app /Applications/
open /Applications/Kalvender.app

Architecture

SwiftUI + WidgetKit. The app (App/) is just a minimal container with a preview — everything interesting lives in the widget extension (Widget/) and the shared logic (Shared/).

• Pure calendar math. Shared/CalendarMath.swift builds the month grid with Calendar(identifier: .iso8601). Shared/Holidays.swift computes every country's holidays locally: Easter-based ones via computus (the anonymous Gregorian algorithm), weekday-ruled ones via "nth weekday of the month" rules, the rest fixed dates. No calendar data is ever fetched. Nationwide holidays only — regional days and "observed" shifts (US/UK) are not included; the United Kingdom follows England & Wales.
• Interactivity via App Intents. The ◀ / ▶ buttons run ChangeMonthIntent and every day cell runs SelectDayIntent, directly in the widget process. This also means taps inside the calendar don't open the app — only taps outside the buttons do (a WidgetKit behavior that cannot be disabled).
• Settings via AppIntentConfiguration. ConfigurationIntent declares the parameters; macOS renders the panel automatically. There is deliberately no "system language" option: the string table covers exactly the languages offered, so a system language outside the list can never produce a half-translated widget.
• State (month offset and selection) lives in the widget process's own UserDefaults — no App Group is needed since the intents and the timeline provider run in the same process. State is shared between widget instances.
• Timeline: a single entry refreshed at the next midnight, which moves the today marker and resets month browsing.

Development notes

The Xcode project is generated with XcodeGen from project.yml; the generated Kalvender.xcodeproj is checked in, so just opening the project works. After changing project.yml — and whenever new source files are added (they are listed explicitly in the project file) — run xcodegen generate.

When the widget's configuration schema changes (new settings, changed enum cases): bump MARKETING_VERSION/CURRENT_PROJECT_VERSION in project.yml and restart the widget service (killall chronod), otherwise placed widgets may freeze on a cached descriptor of the old schema.

The app icon is generated programmatically; the master image is Shared/Assets.xcassets/AppIcon.appiconset/icon_512x512@2x.png (1024×1024) and the other sizes are downscales of it.

License

MIT — in short: anyone may use, copy, modify and redistribute the code, commercially too, as long as the copyright and license text are preserved. The software is provided as-is, with no warranty and no liability for the author.