title: How to change BottomNavigationBarItem icon when selected, Flutter
body: <p>I am new to Flutter. I have a <code>BottomNavigationBar</code> with 4 items. I want to change icon of the item when pressed. Please help.</p>
  
  <p>This is what I have done so far.</p>
  
  <pre><code>bottomNavigationBar : new BottomNavigationBar(
          currentIndex: index,
          onTap: (int index) {
            setState(() {
              this.index = index;
            }
            );
            _navigateToScreens(index);
          },
          type: BottomNavigationBarType.fixed,
          items: [
            new BottomNavigationBarItem(
                backgroundColor: Colors.white,
                icon: new Image.asset('images/1.0x/icon1.png'),
                title: new Text("Route1", style: new TextStyle(
                    color: const Color(0xFF06244e), fontSize: 14.0))),
            new BottomNavigationBarItem(
                icon: new Image.asset('images/1.0x/icon2.png'),
                title: new Text("Route2", style: new TextStyle(
                    color: const Color(0xFF06244e), fontSize: 14.0))),
            new BottomNavigationBarItem(
                icon: new Image.asset('images/1.0x/icon3.png'),
                title: new Text("Route3", style: new TextStyle(
                    color: const Color(0xFF06244e), fontSize: 14.0),)),
            new BottomNavigationBarItem(
                icon: new Image.asset('images/1.0x/icon4.png'),
                title: new Text("Route4", style: new TextStyle(
                    color: const Color(0xFF06244e), fontSize: 14.0),))
          ]);
  </code></pre>