title: How to add asset image in app bar as an action icon in Flutter application?
body: <p><strong>Problem</strong>
  I am trying to add a logout image icon in appbar of flutter screen. I have created a asset folder and created directories images/icons/ and placed icons in them. 
  I have mentioned them in pubspec.yaml file. 
  I tried to implement a asset image in appbar but its not working.</p>
  
  <p><strong>Code</strong> </p>
  
  <p><strong>pubspe.yaml</strong></p>
  
  <pre><code>
      name: mtrack_notifications
      description: Flutter application for MTrack Notifications 
  
      dependencies:
        flutter:
          sdk: flutter
        # The following adds the Cupertino Icons font to your application.
        # Use with the CupertinoIcons class for iOS style icons.
        cupertino_icons: ^0.1.2
        http: ^0.11.3+16
        shared_preferences: "^0.4.2"
  
  
      dev_dependencies:
        flutter_test:
          sdk: flutter
  
  
      # For information on the generic Dart part of this file, see the
      # following page: https://www.dartlang.org/tools/pub/pubspec
  
      # The following section is specific to Flutter.
      flutter:
  
        # The following line ensures that the Material Icons font is
        # included with your application, so that you can use the icons in
        # the material Icons class.
        uses-material-design: true
  
        # To add assets to your application, add an assets section, like this:
        # assets:
        #  - images/a_dot_burr.jpeg
        #  - images/a_dot_ham.jpeg
        assets:
        - assets/images/icons/like.png
        - assets/images/icons/logout.png
        # An image asset can refer to one or more resolution-specific "variants", see
        # https://flutter.io/assets-and-images/#resolution-aware.
  
        # For details regarding adding assets from package dependencies, see
        # https://flutter.io/assets-and-images/#from-packages
  
        # To add custom fonts to your application, add a fonts section here,
        # in this "flutter" section. Each entry in this list should have a
        # "family" key with the font family name, and a "fonts" key with a
        # list giving the asset and other descriptors for the font. For
        # example:
        # fonts:
        #   - family: Schyler
        #     fonts:
        #       - asset: fonts/Schyler-Regular.ttf
        #       - asset: fonts/Schyler-Italic.ttf
        #         style: italic
        #   - family: Trajan Pro
        #     fonts:
        #       - asset: fonts/TrajanPro.ttf
        #       - asset: fonts/TrajanPro_Bold.ttf
        #         weight: 700
        #
        # For details regarding fonts from package dependencies,
        # see https://flutter.io/custom-fonts/#from-packages
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/gCqOT.png" rel="noreferrer">Click to see the IDE screenshot here</a></p>
  
  <p><strong>Appbar code</strong></p>
  
  <pre><code>
  
  
      @override
        Widget build(BuildContext context) {
          //build a form widget using the form key we created above
          return new Scaffold(
            appBar: new AppBar(
              title: new Text(StringRef.appName),
              actions: [
  
            new Center(
            child:new Text(
              userName,
              textScaleFactor: 1.5,
              style: new TextStyle(
                fontSize: 12.0,
                color: Colors.white,
              ),
            )),
            new IconButton(
              icon: new Icon(Icons.close),
              tooltip: 'Closes application',
              onPressed: () => exit(0),
            ),
  
            new IconButton(
              icon: new Image.asset('images/icons/logout.png'),
              tooltip: 'Closes application',
              onPressed: () => exit(0),
            ),
  
              ],
            ),
  
  </code></pre>