Flutter & Dart: 50+ Tips & Tricks for App Development

Text(
	"Title",
	style:Theme.of(context).textTheme.title),
Text(
	"Headline",
	style:Theme.of(context).textTheme.headline),
Text(
	"Subhead",
	style:Theme.of(context).textTheme.subhead),
Text(
	"Button",
	style:Theme.of(context).textTheme.button),
Text(
	"Caption",
	style:Theme.of(context).textTheme.caption),
Text(
	"Body1",
	style:Theme.of(context).textTheme.body1),
Text(
	"Body2",
	style:Theme.of(context).textTheme.body2),

FractionallySizedBox(
	widthFactor: 0.75,
	heightFacter: 0.75,
	child: Container(color: Color.orange),
)

    var fooParsed = int.parse(5800);
	print(fooParsed);//5800

  var fooParsedDouble = int.parse(84545.25616);
  print(fooParsedDouble);//84545.25616

fooLogin{
	required String email,
	
	required String password
}){
	try{
		var user =await _data.login(email,password);		
	} on FechDataException catch(error){
		print('Exception Data : $error');
	}
}

//insted of
if(title == null){
	title = "Title";
}

//use dellow
title ?? = "Title";

ListView.separated(
	itemCount: Items.length,
	itemBuilder: (ctx,i) => ExampleItem(),
	
	//Separator can be any widget.
	separatorBuilder: (ctx,i)=>const Divider(),
);

//Good
var title;

//Bad 
var title = null;

//Insted of this

bool isAndroid = true;

getDeviceType(){
	if(isAndroid)(return "Android";)
	else{return "Other";}
}

//Use bellow

bool isAndroid = true;
isAndroid ? "Android" : "Other";

Theme(
     data:ThemeData(...),
     child:TextFormField(
	decoration: const InputDecoration(
	   icon: (Icons.person),
	   hintText:'What do people call you?',
	   labelText:'Name *',
     	),
     	validator: (value) {
		return value!l.contains('@')? 'Do not use @ char':null;
     	}
    ),
)

class Person {
	String name;
	int age;
	Person(this.name, this.age);

	void data() => print("$name is $age years old.");
}


//Without Cascade Notation
Person person = Person("Richard", 50);

person.age = 22;
person.name +=" Parker";
person.data();

//Cascade Notation with Object of Person
Person("Jian", 21)
..age = 22

..Name +=" Yang"
..data();

//Cascade Notation with List
<String>["Natasha", "Steve", "Peter", "Tony"]
..sort()
..forEach((name) => print("\n$name"));

class InkWellCard extends StatelessWidget {

	@override
	Widget build(BuildContext context) {
	(
		return Card(
			elevation: 3.0,
			child: Ink(
			    child:InkWell (
				onTap: () => print("Ordering.."),
				child: Text("Order Bagels"),
			    ),
 			),
	);}
}

assert(title != null, "Title string cannot be null.");

final String name = 'Flutter And Dart Tips and Triks';

print('Hello ${name.split(" ")[0]}');
print('Hello ${name.split(" ")[2]});

Container(
	width: double.maxFinite,
	height: double.maxFinite,
	decoration:BoxDecoration(
	     image:DecorationImage(		
		image:NetworkImage('https://bit.ly/2322da),
	     ),),
	child:Center(
		child:Text('Flutter.dev',
		style: (color: Colors.red),),),
);

import 'package:flutter/foundation.dart';

print('Ils Release Mode: $kReleaseMode');

GestureDetector(
	behavior: HitTestBehavior.opaque,
	ontTap: () => print('Tap!'),
	child: Container(
	height: 250
	width: 250
	child: Center(child: Text('Gesture Test')),
	),
),

for (var entry in items.entries) {

	//Print the keys and values
	print('${entry.key}: ${entry.value}');
}

class someAPI {
    Future<int> getThings() => Future.value(3000);
    Future<int> getItems() => Future.value(300);
    Future<int> getStuff() => Future.value(30);
}

final api = someAPI();
final values =
await Future.wait([
    api.getThings(),
    api.getltems(),
    api.getStuff(),
])

Fleible (
    child:GridView.count (
       crossAxisCount:
            (orientation == Orientation.portrait) ? 2:3,
        mainAxisSpacing: 4.0,
        crossAxisSpacing: 4.0,
        padding:const EdgeInsets.all(4.0),
       childAspectRatio:
        (orientation == Orientation.portrait) ? 1.0:1.3,
       children: someList.map((catData) =>
        aListitemWidget(catData)).toList(),
     ),
);

import 'dart:math';

...

int min = 0;

int max = someList.length - 1;
Random rnd = new Random();

int r = min + rnd.nextInt(max - min);
return someList[r];

import 'package"flutter/services.dart';
...

void main() async{
    await
    SystemChrome.setPreferredOrientations
    [DeviceOrientation.portraitUp]);

    runApp(Appan());
}

import 'dart.io' show Platform

'''
if (Platform.isIOS) {
    doSomethingforIOS();
}

if (Platform.isAndroid) {
    doSomethingforAndroid();
}

const Map color = {

	50:Color.fromRGBO(255, 207, 68, .1),
	100:Color.fromRGBO(255, 207, 68, .2),
	200:Color.fromRGBO(255, 207, 68, .3),
	300:Color.fromRGBO(255, 207, 68, .4),
	400:Color.fromRGBO(255, 207, 68, .5),
	500:Color.fromRGBO(255, 207, 68, .6),
	600:Color.fromRGBO(255, 207, 68, .7),
	700:Color.fromRGB(255, 207, 68, .8),
	800:Color.fromRGB(255, 207, 68, .9),
	900:Color.fromRGB(255, 207, 68, 1),
};

const MaterialColor custom_color =MaterialColor(OxFFFFCF44, color);

import 'package:flutter/services.dart';

void main(){
	SystemChrome.setEnabledSystemUiMode(
	    SystemUiMode.manual,
	    overlays: [],
	);
}

Row(
   crossAxisAlignment:
       CrossAxisAlignment.center,
	   children: [
		Expanded(
		    child:Image.asset('images/pic1.jpg'),
		),
		Expanded(
		    child:Image.asset('images/pic2.jpg'),
		),
		Expanded(
		    child:Image.asset('images/pic3.jpg'),
		),
	  ]
);

//Page 1
Hero(
    tag:"FlyingHero",
	child:Icon(
	   Icons.party_mode_outlined,
	   size: 50.0,
	),
);



//Page 2
Hero(
    tag:"FlyingHero",
	child:Icon(
	   Icons.party_mode_outlined,
	   size: 150.0,
	),
);

Stack(
    children:[
	Container(
	    width: 100,
	    height: 100,
	    color: Colors.red,
	),
	Container(
	    width: 90,
	    height: 90,
	    color: Colors.green,

	),

	Container(
	    width: 80,
	    height: 80,
	    color: Colors.blue,
	),
     ],
);

enum Cities { Tehran, Zanjan, Tabriz}

extension ToString on Cities {
    String get name => toString().split('.').last;
}

void main() {
    print(Cities.Tehran.name);
    print(Cities.Zanjan.name);
    print(Cities.Tabriz.name);
}

class WelcomeToTheCity {

    //Difining call method
    String call(String str1, String str2, String str3) =>'Welcome to $str1$str2$str3;
}


void main(){
    var welcomeToCity = WelcomeToTheCity();

    //Calling the class through its instance
    var welcomeMsg = welcomeToCity('SanDiego','CA','USA');
    print(welcomeMsg);
}

inkWell(
    splashColor: Colors.red,
    onTap: () {},
    child: Card(
       elevation: 5.0.
       child: Text('Click This',
           style:Theme.of(context).text Theme.headline2,
    ),
     ),
);

Center(
    child: Text('This is a very nice text ',
    style: TextStyle(
         fontWeight: FontWeight,
         color: Colors.white,
         fontSize: 20,
         background: Paint()
         ..strokWidth =30.0
         ..color = Colors.red
         ..style = PaintingStyle.stroke
         ..strokeJoin = StrokJoin.round),
    ),
)

Center(
    child: Row(children: [
    Expanded(
       chiled:FittedBox(    
         child:Text("When looking at a page's layout, it is a well-known truth that "the reader will be distracted by the readable." content." ,
          maxLines: 1,
        style: (fontSize: 23),
          ),
      ),
    ),
      ]
    ),
)

ListView(
     scrollDirection: Axis.horizontal,
     children: [
    ///Some object
     ],
);

Scaffold(
    floatingActionButtonLocation:
    FloatingActionButtonLocation.centerFloat,

    floatingActionButton:
    FloatingActionButton(
    onPressed: () {},
    child: Icon(Icons.settings_voice),
    ),

...
);

final snackBar =SnackBar(
  content:
    const Text('Amazing SnackBar!'),
    action:SnackBarAction(
        label:'Undo',
        onPressed: () {
        //Do somthing
        },
    ),
);

showDialog(
     context: context,
     barrierDismissible:false,
     builder: (BuildContext context) =>
    AlertDialog(
       title:const Text('This is a title'),
       content:
        const Text('This is a description'),
        actions: [
            TextButton(
            onPressed: () =>
              Navigator.pop(context,'Cancel'),
              child: const Text('Cancel'),
            ),
    . 
    .
    .

            TextButton(
            onPressed: () =>
            Navigator.pop(context, 'OK’),
            child: const Text('Ok’),
            ),
        ],
    ),
);

ElevatedButton(
    onPressed: () {}.
    style:
    ElevatedButton.styleFrom(
    shape:CircleBorder(),
    padding:EdgeInsets.all(30),
    ),
    child: Icon(
    Icons.add,
    size: 50,
    ),
)

Center(
   child: ShaderMask(
	blendMode: BlendMode.srcin,
	shaderCallback: (Rect bounds) {
	    return const LinearGradient(
		colors: [Colors.red, Colors.green],
		tileMode: TileMode.clamp,
	    ).createShader(bounds); },
   child:
	const Text('This is a colorful Text',
	      style:TextStyle (fontSize: 36),
        ), 
   ),
)

double _size =500;

bool _large = false;

void _updateSize() {
    setState(() {
         _size = _large ? 250.0 : 100.0 ;
	 _large = !_large;
	});
}

GestureDetector(
       onTap: () => _updateSize(),
       child: Container(
	   color: Colors.amberAccent,
	   child: AnimatedSize(
		vsync:this,
		curve: Curves.easeInCirc,
		duration:
		   const Duration(seconds: 2),
		   child:FlutterLogo(size: _size),
	   ),
      ),
);

Column(
    children: [
	//The Original image
	Image.netWork(_imageUrl),
	
	ColorFiltered(
	     colorFilter:
	   	const ColorFilter.mode(Colors.grey,
		    BlendMode.saturation),

	     child: Image.network (_imageUrl),
	),
     ]
);

Text('Important Text',
    style: TextStyle(
	color: Colors.black,
	fontSize: 50,
	fontWeight: FontWeight.bold,
	shadows: [
	    Shadow(
		color: Colors.red[500]!,
		offset:const Offset(-50, -50),
		blurRadius: 5),
	    Shadow(
		color: Colors.green[200]!,
		offset: const Offset(50, 50),
		blurRadius: 5),
	],
     ),
);

LayoutBuilder(
    builder: (context, constraints) {
	if(constraints.maxWidth >= 750) {
	    return Container(
		color: Colors.green,
		height: 100,
		width: 100,
	    );
	}else{
	    return Container(
		color: Colors.yellow,
		height: 100,
		width: 100,
	    );
	}
    },
)

AnimatedContainer (
     width: _width,
     height: height,
     decoration:BoxDecoration(
    color: _color,
    borderRadius: _borderRadius,
     ),
     duration:Duration(seconds: 1),
     curve: Curves.fastOutSlowIn,
)

SliverAppBar (
    pinned: _pinned,
    snap: _snap,
    floating: _floating,
    expandedHeight: 160.0,
   
    flexibleSpace:
    const FlexibleSpaceBar(
       title: Text('SilverAppBar'),
       background:FlutterLogo(),
    ),
)

AnimatedOpacity(
    opacity: _opacity,
    duration: const Duration(seconds: 1),
    curve: Curves.bounceinOut,
 //The animatedOpacity widget must be a child of the green box.
   
    child:Container(
    width: 200.0,
    height: 200.0,
    color: Colors.green,
    ),
)

Wrap(
   children:List.generate(10,
    (index) =>Container(
        margin:const EdgeInsets.all(10),
        color: Colors.green,
        height: 100,
        width: 100,
    ),
    ),
);

SlideTransition(
    position: _offsetAnimation,
    child:const Padding(
        padding: EdgeInsets.all(8.0),
    child: FlutterLogo(size: 150.0),
    ),
)

FadeTransition (
      opacity: _animation,
      child:const Padding(
          padding:EdgeInsets.all(8),
      child:FlutterLogo(),
      ),
)

AnimatedCrossFade(
    crossFadeState: _isFirst    
    ? CrossFadeState.showFirsy: 
    CrossFadeState.showSecond,
    duration: const Duration(seconds: 1),
    firstCurve: Curves.easeInCubic,
    secondCurve: Curves.easeInCirc,
    
   firstChild:
    const FlutterLogo(style:
        FlutterLogoStyle.horizontal,
        size: 100.0),
   secondChild:
        const FlutterLogo(style:
        FlutterLogoStyle.stacked,
        size: 100.0),
)

CupertinoContextMenu(
    child: Container(color: Colors.red),
    actions: [
        CupertinoContextMenuAction(
       child:const Text('Action one'),
       onPressed: () =>
        Navigator.pop(context),
       ),
    ],
)

BackdropFilter (
    filter:ImageFilter.blur(
    sigmax: 10.0,
    sigmayY: 10.0,
),
    child:Container(
    color:Colors.black.withOpacity (0.2),
    ),
)

Column(
     children: [
    Container(
       color: Colors.red,
       height: 50,
       width: 50,
     ),
    Spacer(),
    Container(    
       color: Colors.green,
       height: 50,
       width: 50,
    ),
    ],
)

FractionallySizedBox(
     widthFactor: 0.5,
     heightFactor: 0.25,
     child:ElevatedButton(
    onPressed: () {},
    child: Text('Click Me'),
     ),
),

AnimatedSwitcher(
    duration: const Duration(milliseconds: 500),
    transitionBuilder: (Widget child,
    Animation animation) {
    return ScaleTransition(child: child,scale: animation)
    },
    child: Text('$_count',
    key: ValueKey(_count) , style:
       Theme.of(context).textTheme.headline4,
    ),
),

CupertinoAlertDialog(
    title:Text("This is the title"),
    content:Text("This is the content"),
    actions: [
    CupertinoButton(
        child: Text('Cancel'),
        onPressed: () => Navigator.of(ctx).pop();
    ),
    CupertinoButton(
        child: Text('I agree'),
        onPressed: (){
        print('I agreed'),
        Navigator.of(ctx).pop();
        },
        ),
   ],
)

Container(
    child:Center(
    child:CupertionButton(
       onPressed: () {},
       child: Text("CupertionButton Widget"),
    ),
    ),
),

Container(
    child:Center(
    child:CupertionButton.filled(
       onPressed: () {},
       child: Text("CupertionButton Widget"),
    ),
    ),
),

Flow(
    delegate: FlowMenuDelegate(
    menuAnimation: menuAnimation),
    children:
    menultems.map(
        (IconData icon) =>
        flowMenultem(icon)).toList(),
    ),
);

Flexible(
     child:Text('Flutter Text Overflow while adding long text. 
                 How to wrap text in flutter',
        style:TextStyle(fontSize: 20),
     ),
)

LinearProgressindicator(
    value: controller.value,
    semanticsLabel:'Linear progress indicator',
)

CheckboxListTile(
      value: _isChecked,
      onChanged: (bool value) {
    setState(() {
       _isChecked = value;
    });
      },
)

PageView(
    children: [
    Container(
        color: Colors.pink,
        child: Center(
        child: Text('Page 1'),
       ),
    ),
    Container(
        color: Colors.cyan,
        child: Center(
        child: Text('Page 2'),
       ),
    ),
  ],
)