SZ Core

A lightweight Flutter package that provides reusable widgets, responsive sizing, utility methods, dialogs, navigation helpers, and a simple API caller to speed up Flutter application development.

Features

  • ✅ Responsive UI scaling (.w, .h, .r, .sp)
  • ✅ Base Activity & Fragment architecture
  • ✅ Built-in API caller (GET,POST,PUT,PATCH & DELETE)
  • ✅ Toasts, dialogs & pickers
  • ✅ Navigation helper
  • ✅ Phone, Website & WhatsApp launcher
  • ✅ Keyboard helper
  • ✅ Date & Time formatting
  • ✅ Random Dark Color generator
  • ✅ Hex Color extension

Included Classes

  • SZCore
  • SZActivity
  • SZFragment
  • SZApiCaller
  • SZApiSetting
  • SZShow
  • SZText
  • SZButton
  • SZIconButton
  • SZTextField

Installation

Add the package to your pubspec.yaml.

dependencies:
  sz_core: ^1.0.9

Then run

flutter pub get

Import

import 'package:sz_core/sz_core.dart';

Initialization

Initialize SZCore before runApp().

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await SZCore.init();

  runApp(const MyApp());
}

With Base URL

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await SZCore.init(
    baseURL: "https://example.com/api/",
  );

  runApp(const MyApp());
}

Custom API Settings

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  SZApiSetting.init(
    "https://example.com/api/",
    keyStatus: "status",
    keyMessage: "message",
    keyData: "data",
    keyInternet: "internet", 
    defaultHeader: {
      "Authorization": "Bearer TOKEN"
    }
  );

  await SZCore.init();

  runApp(const MyApp());
}

You can update custom setting directly from anywhere like

SZApiSetting.defaultHeader = {
   "Authorization": "Bearer UPDATED TOKEN"
};

Responsive Size

SZCore.init() automatically calculates the screen scale.

Use the extensions anywhere.

Container(
  width: 120.w,
  height: 60.h,
  padding: EdgeInsets.all(12.r),
  child: SZText(
    "Hello",
    fontSize: 16.sp,
  ),
)
Extension Description
.w Width scaling
.h Height scaling
.r Radius scaling
.sp Responsive font size

SZActivity

Replace State with SZActivity.

Replace build() with buildContent().

class HomeActivity extends StatefulWidget {
  const HomeActivity({super.key});

  @override
  State<HomeActivity> createState() => _HomeActivityState();
}

class _HomeActivityState extends SZActivity<HomeActivity> {

  @override
  Widget buildContent(BuildContext context) {
    return const SizedBox();
  }
}

Available Methods

showDialog("Loading...");

hideDialog();

open(const SecondActivity());

onResume();

onPaused();

SZFragment

Replace State with SZFragment.

Replace build() with buildContent().

class HomeFragment extends StatefulWidget {
  const HomeFragment({super.key});

  @override
  State<HomeFragment> createState() => _HomeFragmentState();
}

class _HomeFragmentState extends SZFragment<HomeFragment> {

  @override
  Widget buildContent(BuildContext context) {
    return const SizedBox();
  }
}

Available Methods

showDialog("Loading...");

hideDialog();

open(const SecondActivity());

onResume();

onPaused();

SZCore

Open Activity

Open a new activity:

await SZCore.open(
  context,
  const HomeActivity(),
);

Parameters

Parameter Default Description
finish false Closes the current activity before opening the new activity.
onlyOne false Clears all previous activities and opens the new activity as the only active activity.

Example

await SZCore.open(
  context,
  const HomeActivity(),
  finish: true,
  onlyOne: true,
);

Hide Keyboard

SZCore.hideKeyboard(context);

Screen Size

final size = await SZCore.getScreenSize();

print(size.width);
print(size.height);

Date Formatting

Server format

SZCore.formattedDate(DateTime.now());

Output

2026-07-07

Display format

SZCore.formattedDate(
  DateTime.now(),
  server: false,
);

Output

7 Jul 2026

Time Formatting

Server

SZCore.formattedTime(DateTime.now());

Output

14:30

Display

SZCore.formattedTime(
  DateTime.now(),
  server: false,
);

Output

2:30 PM

Random Dark Color

Color color = SZCore.getRandomDarkColor();

Debug Log

SZCore.printLog("Hello");

Prints only in Debug mode.

Open Phone Dialer

SZCore.openCall("9876543210");

Open Website

SZCore.openWebsite(
  "https://flutter.dev",
);

Open WhatsApp

SZCore.openWhatsApp(
  "919876543210",
  message: "Hello",
);

Hex Color Extension

Color color = "#2196F3".toColor();

SZShow

Toast

SZShow.toast("Saved Successfully");

Custom

SZShow.toast(
  "Error",
  bg: Colors.red,
  color: Colors.white,
  size: 14,
);

Dialog

SZShow.dialog(
  context,
  "Success",
  "Data Saved Successfully",
);

Two Buttons

SZShow.dialog(
  context,
  "Delete",
  "Delete this record?",
  btn1: "Yes",
  btn2: "No",
  b1Click: () {

  },
  b2Click: () {

  },
);

Custom Widget

SZShow.dialog(
  context,
  "",
  "",
  buildContent: (setState) {
    return const Text("Custom Widget");
  },
);

Date Picker

SPair date = await SZShow.dateSelect(
  context,
  null,
);

Time Picker

SPair time = await SZShow.timeSelect(
  context,
  null,
);

Year Picker

int year = await SZShow.yearSelect(
  context,
  2025,
);

SZApiCaller

Supports both GET and POST requests.

GET Request

SZApiCaller(
  context,
  this,
  1,
  null,
  "Loading...",
  "users",
).then((response, key) {

});

POST Request

SZApiCaller(
  context,
  this,
  2,
  jsonEncode(data),
  "Please wait...",
  "login",
).then((response, key) {

});

PUT,PATCH,DELETE Request

You can use below enum

enum SZMethod { get, post, delete, put, patch }

SZApiCaller(
  context,
  this,
  2,
  jsonEncode(data),
  "Please wait...",
  "login",
  method = SZMethod.put
).then((response, key) {

});

Custom Header

SZApiCaller(
  context,
  this,
  1,
  null,
  null,
  "users",
  customHeader: {
    "Authorization": "Bearer TOKEN"
  },
).then((response, key) {

});

Logout Callback

SZCore.logoutCallback = () {
  // Navigate to Login Screen
};

If the API response contains "session expire", the callback is automatically invoked.

Requirements

  • Flutter SDK >= 3.0.0

Contributing

Contributions, issues, and feature requests are welcome.

License

This project is licensed under the MIT License. See the LICENSE file for details.

Libraries

sz_core
sz_core_method_channel
sz_core_platform_interface