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
✅ Native Android & iOS device information
✅ Application information
✅ Dynamic User-Agent generation

Included Classes

SZCore
SZActivity
SZFragment
SZApiCaller
SZApiSetting
SZShow
SZText
SZButton
SZIconButton
SZTextField

Installation

Add the package to your pubspec.yaml.

dependencies:
  sz_core: ^2.1.1

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"
};

Device Information

SZCore provides native device and application information through Android and iOS platform channels.

The DeviceInfo model contains application, operating system, device, and hardware information.

Get Device Information

final deviceInfo = await SZCore.getDeviceInfo();

Example:

final deviceInfo = await SZCore.getDeviceInfo();

print(deviceInfo.appName);
print(deviceInfo.appVersion);
print(deviceInfo.appBuild);

print(deviceInfo.platform);
print(deviceInfo.osName);
print(deviceInfo.osVersion);

print(deviceInfo.model);
print(deviceInfo.manufacturer);
print(deviceInfo.brand);

print(deviceInfo.identifier);//Android Device Id / IOS ID

DeviceInfo Properties

Property	Description
`platform`	Platform name, e.g. Android or iOS
`appName`	Application display name
`appVersion`	Application version
`appBuild`	Application build number
`model`	Device model
`manufacturer`	Device manufacturer
`brand`	Device brand
`device`	Android device code name
`product`	Android product name
`osName`	Operating system name
`osVersion`	Operating system version
`sdk`	Android SDK/API level
`abis`	Supported CPU architectures
`deviceName`	User-visible device name
`identifier`	Platform-provided identifier

Example Output

Android:

Platform      : Android
App Name      : My App
App Version   : 1.2.0
App Build     : 25
Manufacturer  : Samsung
Brand         : Samsung
Model         : SM-S928B
OS Name       : Android
OS Version    : 15
SDK           : 35
ABIs          : arm64-v8a
identifier    : b3e32457fd3ec2a4

iOS:

Platform      : iOS
App Name      : My App
App Version   : 1.2.0
App Build     : 25
Model         : iPhone
OS Name       : iOS
OS Version    : 18.6
identifier    : 11112222222332

User-Agent

SZCore can generate a dynamic User-Agent using the application and device information.

final headers = await SZCore.getDefaultHeader();

Example Android:

My App/1.2.0 (Android 15; Samsung SM-S928B; Build 25)

Example iOS:

My App/1.2.0 (iOS 18.6; iPhone; Build 25)

You can use the generated header with your API requests:

final headers = await SZCore.getDefaultHeader();

print(headers["User-Agent"]);

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();

 SZCore.printLog(size.width);
 SZCore.printLog(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,
);

Widgets

`SZText`

A customizable text widget with support for icons, required indicators, shadows, and responsive font sizing.

const SZText(
  'Welcome to SZ Core',
  fontSize: 16,
  fontWeight: FontWeight.bold,
);

const SZText(
  'Email Address',
  required: true,
  icon: Icons.email,
);

`SZButton`

A customizable button with support for icons, colors, borders, and disabled states.

SZButton(
  text: 'Login',
  onClick: () {
    login();
  },
);

SZButton(
  text: 'Delete',
  icon: Icons.delete,
  btnColor: Colors.red,
  onClick: deleteItem,
);

`SZIconButton`

A compact icon button with support for custom widgets and long-click actions.

SZIconButton(
  icon: Icons.edit,
  onClick: () {
    editProfile();
  },
);

SZIconButton(
  icon: Icons.delete,
  bgColor: Colors.red,
  onClick: deleteItem,
  onLongClick: showDeleteConfirmation,
);

`SZTextField`

A customizable text field with support for icons, labels, password mode, and keyboard configuration.

SZTextField(
  hint: 'Enter your name',
  controller: nameController,
);

SZTextField(
  hint: 'Password',
  obscureText: true,
  suffixIcon: Icons.visibility,
);

`SZDropDown`

A generic dropdown widget supporting any object type.

SZDropDown<Pair>(
  true,
  selectedCountry,
  countries,
  (value) {
    setState(() {
      selectedCountry = value;
    });
  },
  toStringConvert: (item) => item.name,
);

`SZAutoComplete`

An autocomplete widget with asynchronous search support.

SZAutoComplete<Pair>(
  isEnable: true,
  value: selectedUser,
  onSearch: (keyword) async {
    return await searchUsers(keyword);
  },
  displayText: (item) => item.name,
  onSelected: (item) {
    selectedUser = item;
  },
);

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.

SZ Core

Features

Included Classes

Installation

Import

Initialization

With Base URL

Custom API Settings

Device Information

Get Device Information

DeviceInfo Properties

Example Output

User-Agent

Responsive Size

SZActivity

Available Methods

SZFragment

Available Methods

SZCore

Open Activity

Parameters

Example

Hide Keyboard

Screen Size

Date Formatting

Time Formatting

Random Dark Color

Debug Log

Open Phone Dialer

Open Website

Open WhatsApp

Hex Color Extension

SZShow

Toast

Dialog

Date Picker

Time Picker

Year Picker

Widgets

SZText

SZButton

SZIconButton

SZTextField

SZDropDown

SZAutoComplete

SZApiCaller

GET Request

POST Request

PUT,PATCH,DELETE Request

Custom Header

Logout Callback

Requirements

Contributing

License

Libraries

sz_core package

`SZText`

`SZButton`

`SZIconButton`

`SZTextField`

`SZDropDown`

`SZAutoComplete`