How to change the appBar back button color

I cannot figure out how to change the appBar's automatic back button to a different color. it's under a scaffold and I've tried to research it but I can't wrap my head around it.

return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.white,
        title: Image.asset(
          'images/.jpg',
          fit: BoxFit.fill,
        ),
        centerTitle: true,
      ),

You have to use the iconTheme property from the AppBar , like this:

appBar: AppBar(
  iconTheme: IconThemeData(
    color: Colors.black, //change your color here
  ),
  title: Text("Sample"),
  centerTitle: true,
),

Or if you want to handle the back button by yourself.

appBar: AppBar(
  leading: IconButton(
    icon: Icon(Icons.arrow_back, color: Colors.black),
    onPressed: () => Navigator.of(context).pop(),
  ), 
  title: Text("Sample"),
  centerTitle: true,
),

Even better, only if you want to change the color of the back button.

appBar: AppBar(
  leading: BackButton(
     color: Colors.black
   ), 
  title: Text("Sample"),
  centerTitle: true,
),

you can also override the default back arrow with a widget of your choice, via 'leading':

leading: new IconButton(
  icon: new Icon(Icons.arrow_back, color: Colors.orange),
  onPressed: () => Navigator.of(context).pop(),
), 

all the AppBar widget does is provide a default 'leading' widget if it's not set.

It seemed to be easier to just create a new button and add color to it, heres how i did it for anyone wondering

Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        leading: BackButton(
            color: Colors.black
        ),

You can also set leading icon color globally for the app

MaterialApp(
  theme: ThemeData(
    appBarTheme: AppBarTheme(
      iconTheme: IconThemeData(
        color: Colors.green
      )
    )
  )
)

Set back button color globally

MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      theme: ThemeData(
        appBarTheme: AppBarTheme(
          backgroundColor: Colors.white,
          iconTheme: IconThemeData(color: Colors.black), // set backbutton color here which will reflect in all screens. 
        ),
      ),
      home: LoginScreen(),
    );

Also,

To change SliverAppBar

 SliverAppBar(
            iconTheme: IconThemeData(
              color: Colors.white, //change your color here
            ),

AppBar(        
    automaticallyImplyLeading: false,
    leading: Navigator.canPop(context)
        ? IconButton(
            icon: Icon(
              Icons.arrow_back,
              color: Colors.black,
              size: 47,
            ),
            onPressed: () => Navigator.of(context).pop(),
          )
        : null,
);

To customise the leading icon, you may want to mimic the functionality of the AppBar widget, which properly handles showing a back button, drawer icon, or close icon, depending on the current context. Here is an example which replaces the default icons.

import 'package:flutter/material.dart';

class TopBar extends StatelessWidget with PreferredSizeWidget {
  static const double _topBarHeight = 60;

  @override
  Widget build(BuildContext context) {
    return AppBar(
      toolbarHeight: _topBarHeight,
      title: Text('Title'),
      automaticallyImplyLeading: false,
      leading: _buildLeadingWidget(context),
    );
  }

  @override
  Size get preferredSize => Size.fromHeight(_topBarHeight);

  Widget _buildLeadingWidget(BuildContext context) {
    final ScaffoldState scaffold = Scaffold.of(context);
    final ModalRoute<dynamic> parentRoute = ModalRoute.of(context);

    final bool canPop = ModalRoute.of(context)?.canPop ?? false;
    final bool hasDrawer = scaffold?.hasDrawer ?? false;
    final bool useCloseButton = parentRoute is PageRoute<dynamic> && parentRoute.fullscreenDialog;

    Widget leading;
    if (hasDrawer) {
      leading = IconButton(
        icon: const Icon(Icons.menu_rounded),
        onPressed: Scaffold.of(context).openDrawer,
        tooltip: MaterialLocalizations.of(context).openAppDrawerTooltip,
      );
    } else {
      if (canPop) {
        if (useCloseButton) {
          leading = IconButton(
              color: Theme.of(context).colorScheme.onBackground,
              icon: Icon(Icons.close_rounded),
              onPressed: () => Navigator.of(context).maybePop());
        } else {
          leading = IconButton(
              padding: EdgeInsets.all(0),
              iconSize: 38,
              icon: Icon(Icons.chevron_left_rounded),
              onPressed: Navigator.of(context).pop);
        }
      }
    }

    return leading;
  }
}

This class uses the PreferredSizeWidget as a mixin, so you can use it as a replacement for an existing AppBar widget in a Scaffold. Note the _buildLeadingWidget method, which only shows a back button if necessary, and shows a menu button if a drawer is present, or a close button if a full-screen dialog is displayed.

You can use foregroundColor property. For example:

AppBar(
    backgroundColor: Colors.white,
    foregroundColor: Colors.black,
    title: const Text('Black title and back icon on a white AppBar'),
  )

To change the leading color for CupertinoPageScaffold

Theme(
  data: Theme.of(context).copyWith(
    cupertinoOverrideTheme: CupertinoThemeData(
      scaffoldBackgroundColor: Colors.white70,
      primaryColor: Styles.green21D877, // HERE COLOR OF LEADING
    ),
  ),
  child: CupertinoPageScaffold(
    navigationBar: CupertinoNavigationBar(
      brightness: Brightness.light,
      backgroundColor: Colors.white,
      middle: Text('Cupertino App Bar'),
    ),
    child: Container(
      child: Center(
        child: CupertinoActivityIndicator(),
      ),
    ),
  ),
)

  appBar: AppBar(
          iconTheme: IconThemeData(
            color: Colors.white, //modify arrow color from here..
          ),
      );

You can use icon theme:

iconTheme: IconThemeData(
    color: Colors.black, // <= You can change your color here.
),

You can customize the AppBarWidget, keyword with is important, or you can assign your custom AppBarWidget to appBar property of Scaffold:

import 'package:flutter/material.dart';

double _getAppBarTitleWidth(
    double screenWidth, double leadingWidth, double tailWidth) {
  return (screenWidth - leadingWidth - tailWidth);
}

class AppBarWidget extends StatelessWidget with PreferredSizeWidget {
  AppBarWidget(
      {Key key,
      @required this.leadingChildren,
      @required this.tailChildren,
      @required this.title,
      this.leadingWidth: 110,
      this.tailWidth: 30})
      : super(key: key);

  final List<Widget> leadingChildren;
  final List<Widget> tailChildren;
  final String title;
  final double leadingWidth;
  final double tailWidth;

  @override
  Widget build(BuildContext context) {
    // Get screen size
    double _screenWidth = MediaQuery.of(context).size.width;

    // Get title size
    double _titleWidth =
        _getAppBarTitleWidth(_screenWidth, leadingWidth, tailWidth);

    double _offsetToRight = leadingWidth - tailWidth;

    return AppBar(
      title: Row(
        children: [
          Container(
            width: leadingWidth,
            child: Row(
              mainAxisAlignment: MainAxisAlignment.start,
              children: leadingChildren,
            ),
          ),
          Container(
            color: Colors.green,
            width: _titleWidth,
            padding: const EdgeInsets.only(left: 5.0, right: 5),
            child: Container(
              padding: EdgeInsets.only(right: _offsetToRight),
              color: Colors.deepPurpleAccent,
              child: Center(
                child: Text('$title'),
              ),
            ),
          ),
          Container(
            color: Colors.amber,
            width: tailWidth,
            child: Row(
              children: tailChildren,
            ),
          )
        ],
      ),
      titleSpacing: 0.0,
    );
  }

  @override
  Size get preferredSize => Size.fromHeight(kToolbarHeight);
}

The following is the example about how to use it:

import 'package:flutter/material.dart';
import 'package:seal_note/ui/Detail/DetailWidget.dart';
import 'package:seal_note/ui/ItemListWidget.dart';

import 'Common/AppBarWidget.dart';
import 'Detail/DetailPage.dart';

class MasterDetailPage extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => _MasterDetailPageState();
}

class _MasterDetailPageState extends State<MasterDetailPage> {
  @override
  Widget build(BuildContext context) { 
    return Scaffold(
      appBar: AppBarWidget(leadingChildren: [
        IconButton(
          icon: Icon(
            Icons.arrow_back_ios,
            color: Colors.white,
          ),
        ),
        Text(
          '文件夹',
          style: TextStyle(fontSize: 14.0),
        ),
      ], tailChildren: [
        Icon(Icons.book),
        Icon(Icons.hd),
      ], title: '英语知识',leadingWidth: 140,tailWidth: 50,),
      body: Text('I am body'),
    );
  }
}