flutter - Viewing a greeting screen for a specific period of time -

i have been trying find information creating widget disappears after period of time. trying create greeting page appears once app runs , disappears after couple of seconds; navigating home page afterwards.

what correct direction in order done?

i understand how use showdialog buttons, want greetings view first view when app starts, how correctly use showdialog?

void main() {   runapp( new materialapp(    home: new signin(),//how integrate showdialog flow )) } 

the full code of transition between 'greeting page' , home using pageroutebuilder , navigatorstate.pushreplacement :

import 'dart:async'; import 'package:flutter/material.dart';  void main() {   runapp(new materialapp(     home: new greeting(),   )); }  class greeting extends statefulwidget {   @override   _greetingstate createstate() => new _greetingstate(); }  class _greetingstate extends state<greeting> {   @override   initstate() {     super.initstate();     new timer(const duration(seconds: 5), onclose);   }    @override   widget build(buildcontext context) {     return new scaffold(       body: new align(           alignment: fractionaloffset.center,           child: new column(             mainaxisalignment: mainaxisalignment.center,             children: <widget>[               new text(                 "hello !",                 style: theme.of(context).texttheme.display1,               ),               new row(                 mainaxisalignment: mainaxisalignment.center,                 children: <widget>[                   new text("here's unicorn your"),                   new image.network(                     "https://i.pinimg.com/736x/3b/06/ef/3b06efe25fed62de2960090ff2b8d83a--cute-cartoon-drawings-drawings-of.jpg",                     height: 42.0,                     width: 42.0,                   ),                 ],               )             ],           )),     );   }    void onclose() {     navigator.of(context).pushreplacement(new pageroutebuilder(         maintainstate: true,         opaque: true,         pagebuilder: (context, _, __) => new home(),         transitionduration: const duration(seconds: 2),         transitionsbuilder: (context, anim1, anim2, child) {           return new fadetransition(             child: child,             opacity: anim1,           );         }));   } }  class home extends statelesswidget {   @override   widget build(buildcontext context) {     return new scaffold(       appbar: new appbar(         backgroundcolor: colors.pink,         title: new text("home"),       ),     );   } }