core_utils_kit 0.1.1

Small Flutter utilities: secure key-value storage, date and time formatting, color generation, URL opening, and app lifecycle watching without extra state-management dependencies.

core_utils_kit

Small Flutter utilities: secure key-value storage, date and time formatting, color generation, URL opening, random strings, and app lifecycle hooks. The package adds no state-management dependency.

Features

API	Purpose
KeyValueStore	Key-value store interface with read, write, delete, and deleteAll.
InMemoryKeyValueStore	KeyValueStore backed by a Map. Use it in tests.
SecureStorageService	KeyValueStore backed by flutter_secure_storage.
DateFormats	utcDayStart, convertDate, and formatDuration.
DurationFormatting	toHoursMinutes and toHoursMinutesSeconds extensions.
LifecycleWatcher	Mixin that forwards app lifecycle events to onApp* hooks.
generateMaterialColor, tintColor, shadeColor	Color helpers.
openLink	Opens a Uri with fallback launch modes.
generateRandomString	Random alphanumeric string of a given length.
BuildContextX.afterBuild	Runs a callback after the current build.

Install

flutter pub add core_utils_kit

Usage

Secure storage

final KeyValueStore store = SecureStorageService();
await store.write('token', 'abc123');
final String? token = await store.read('token');

SecureStorageService accepts iOptions and aOptions. The defaults are KeychainAccessibility.first_unlock on iOS and AndroidOptions(resetOnError: false) on Android.

Dates and durations

final String dayStart = DateFormats.utcDayStart();
final String posted = DateFormats.convertDate('2024-03-31T01:30:00+02:00', 'fi');
final String compact = DateFormats.formatDuration(
  const Duration(days: 1, hours: 2, minutes: 3, seconds: 4),
); // 1d:2h:3m:4s
final String clock = const Duration(hours: 5, minutes: 15).toHoursMinutes(); // 05:15

Call initializeDateFormatting('fi') before you use a non-English locale. When you omit the locale, convertDate uses Intl.getCurrentLocale().

Lifecycle

Apply WidgetsBindingObserver before LifecycleWatcher:

class _ScreenState extends State<Screen>
    with WidgetsBindingObserver, LifecycleWatcher<Screen> {
  @override
  void onAppResumed() {}

  @override
  void onAppInactive() {}

  @override
  void onAppPaused() {}

  @override
  void onAppDetached() {}
}

Links, colors, and random strings

final bool opened = await openLink(Uri.parse('https://rocket.art'));
final MaterialColor swatch = generateMaterialColor(const Color(0xFF9BD41E));
final String nonce = generateRandomString(16);

After build

context.afterBuild(() {
  // Run work that must not happen during build.
});

Platforms

The package compiles for every Flutter target. SecureStorageService uses flutter_secure_storage, which supports Android, iOS, macOS, Linux, and Windows. On Linux it needs libsecret.

Storage migration

flutter_secure_storage 11 cannot read Android data that version 9 wrote. An app that upgrades loses its stored tokens and preferences one time. iOS items with the first_unlock accessibility class remain readable.

Example

The example/ app shows the store, the date helpers, and the lifecycle hooks.