I'm learning mobile dev using flutter, with little programming background. Just want to know which is a better practice and does it affect performance of the code. Let say I have 5 RaisedButton
Should I do like this. Or make a different file and access the constructor of the new class? The only difference is the text on the button and the route
children: <Widget>[
RaisedButton(
elevation: 0.1,
child: Text('Attandence Tag'),
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => UserTag()),
);
},
),
RaisedButton(
elevation: 0.1,
child: Text('Add New Student'),
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => CreateUser()),
);
},
),
thanks for answering
If you have special styling it's definitely worth to define it in an other file.
If you want to change the style you just have one widget to change it's easier and it simplify your code.
But (because nothing is perfect), Flutter produce easily spaghetti code, so it's up to you to make it clear the way you want. The best way is the one you feel comfortable with, and you have to try things to discover it.
Related
I am using flutter for development and I want to send app to background or close it when user clicks on back icon on appbar
I have used this answer for reference but apart from exit(0) is nothing working, which is not recommended in iOS.
I have tried following recommendations from other answers but none of it working on iOS.
Navigator.of(context).pop();
Navigator.of(context).maybePop();
Navigator.of(context, rootNavigator: true).pop(context);
Navigator.pushReplacementNamed(context, '/route');
SystemNavigator.pop();
Navigator.pop(context,true);
SystemChannels.platform.invokeMethod('SystemNavigator.pop');
for android following is working properly.
SystemNavigator.pop();
What should I use to close the app within apple guidelines.
EDIT
SystemNavigator.pop(); gives black screen in iOS.
Try this
appBar: AppBar(
leading: IconButton(
icon: Icon(Icons.arrow_back, color: Colors.black),
onPressed: () => Navigator.of(context).pop(),
),
title: Text("Sample"),
centerTitle: true,
),
This may be a duplicate question as I have seen a lot of questions that has to do with iframes, webview and all that but each one gets me more confused as I study them. Currently I am making use of the WebView widget to display a webview in my mobile app. I wish to build for the web now but WebView is not supported for web so I have been seeking for an alternative approach. I got to know about HtmlElementView from the flutter documentation. Trying to research into it but I can not seem to find any clear way I am supposed to use it to solve my problem.
Here is my code:
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: Container(
margin: EdgeInsets.fromLTRB(0, 15, 0, 0),
child: !kIsWeb
? WebView(
initialUrl: this.widget._url,
javascriptMode: JavascriptMode.unrestricted,
onPageStarted: this._pageStarted,
)
: HtmlElementView(
viewType: '',
),
),
),
);
}
From my code, I am building the WebView when not compiled for web and building HtmlElementView when compiled for web. As much as I hate to say it, this is as far as my knowledge can go for now on HtmlElementView. From the docs, viewType is to take a String which I do not really know anything about.
What I wish to do exactly? The contents loaded in WebView is kind of dynamic so I wish to load same in the HtmlElementView. Any help or maybe materials that could help me in this would be so much appreciated as I am new to all these. Thanks.
I'm currently on the same quest and found this handy, simple example:
https://codepen.io/riccio85/pen/wvMeaMe
import 'dart:html';
import 'dart:ui' as ui;
import 'package:flutter/material.dart';
void main() {
// ignore: undefined_prefixed_name
ui.platformViewRegistry.registerViewFactory(
'hello-html',
(int viewId) => IFrameElement()
..width = '500'
..height = '360'
..src = 'https://www.youtube.com/embed/xg4S67ZvsRs'
..style.border = 'none');
runApp( Padding(
padding: EdgeInsets.all(25),
child: SizedBox(
width: 640,
height: 360,
child: HtmlElementView(viewType: 'hello-html'),
),
),
);
}
It's not perfect but it seems to do what I need to. Which is to say, I also end up checking for web in the same way as your example and use webview_flutter otherwise.
Seems to be a bit of a shortcoming with the whole thing at the moment, let's hope the situation improves.
I created a new Flutter app from scratch, in Android Studio. In one of my previous apps, I intentionally used a weird font style. Now, for some reason, the new app has the same fonts. Is it possible that I had stored some "global" font style somewhere in the Android Studio, and now it's getting re-used? How can I get rid of it and revert the "normal" fonts?
Here's the code of one widget and its screenshot in the emulator:
import 'package:flutter/material.dart';
class LoginScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return SafeArea(
child: Container(
child: Column(
children: <Widget>[
RaisedButton(
child: Text('Login'),
onPressed: () {
Navigator.pushNamed(context, '/');
},
),
Text('Login'),
],
),
),
);
}
}
No, there shouldn't be.
In my case it also appeared in the debug app, but disappeared again when I recompiled the project. I haven't seen it in a finished app yet.
I have a MultiBlocProvider assigned for an app that has a Bottom Navigation Bar to navigate through main routes like Home, Search, Wishlist ...
I use setState(){} to change the currentPage for each route.
Recently I've added Blocs to each of them by using flutter_bloc package and I'm using BlocProvider to provide the bloc to each BlocBuilder,
#override
Widget build(BuildContext context) {
return SafeArea(
top: false,
child: Scaffold(
key: _scaffoldKey,
body: PageStorage(
child: Stack(
children: <Widget>[
AnimatedSwitcher(
duration: Duration(milliseconds: 200),
child: BlocProvider<WishlistBloc>(
create: (BuildContext context) => WishlistBloc(WishlistRepository()),
child: currentPage),
),
bottomBar(currentPageScroll)
],
),
bucket: bucket,
),
),
);
}
Is it ok to use MultiBlocProvider to provide all the BlocsProviders I need?
they could be more than 10 providers, would it affect the performance of the app?
It's definitely OK, MultiBlocProvider created for this purposes. But you need to understand, that if you with your creation also send(for e.x.) initialize event which started loading in all 10 blocs some data you will have some issues. So, if you will have some performance issues, please create separate SO question and community will help to find root-cause of this.
I am trying to use Navigator.pop(context); in an appbar but the problem is that it shows a black screen and then you have to press the back button on android then it pops current black screen, so where is this black screen coming from that I don't know and in iPhone there is no back button so that why it is stuck in that screen. Please do help me
This is the code where I am using this Navigator code.
#override
Widget build(BuildContext context) {
return new Scaffold(
backgroundColor: Color.fromRGBO(30, 30, 30, 1.0),
appBar: new AppBar(
elevation: 0.0,
backgroundColor: Color.fromRGBO(30, 30, 30, 1.0),
actions: <Widget>[
new IconButton(
icon: Icon(Icons.settings_power),
onPressed: () {
Navigator.pop(context);
}),
],
title: new Text(
"PROLOG",
style: new TextStyle(color: Colors.white),
),
centerTitle: true,
),
);
}
and the most strange thing is that I am using this piece of code in another class its working fine. So where is the problem...
The reason why you're getting a black/blank screen after calling Navigator.pop(context) is because there's no widget/screen beyond the current Navigator stack.
In Flutter, SystemChannels.platform.invokeMethod('SystemNavigator.pop') is used to remove the topmost Flutter instance. As mentioned in the docs, the method should remove the current Activity from the stack in Android. The behavior is a bit different on iOS though.
If you're trying to implement this function to close the app, this is highly discouraged. This is pointed out on Apple's archived doc. I'm trying to search for an updated reference, but navigating through Apple's Developer docs is challenging.
Anyway, I've made some changes to your code snippet if you'd like to try this out.
Add this in your imports
import 'dart:io' show Platform, exit;
As for the code, exit(int) is used for iOS. It's recommended to use an exit code from the range 0...127 as mentioned in the docs. While SystemChannels.platform.invokeMethod('SystemNavigator.pop') is used for other platforms (mainly Android in this case).
Widget build(BuildContext context) {
return new Scaffold(
backgroundColor: Color.fromRGBO(30, 30, 30, 1.0),
appBar: new AppBar(
elevation: 0.0,
backgroundColor: Color.fromRGBO(30, 30, 30, 1.0),
actions: <Widget>[
new IconButton(
icon: Icon(Icons.settings_power),
// if Platform is iOS call exit(0)
// else call the preferred method
// https://api.flutter.dev/flutter/services/SystemNavigator/pop.html
onPressed: () => Platform.isIOS
? exit(0)
: SystemChannels.platform.invokeMethod('SystemNavigator.pop'),
),
],
title: new Text(
"PROLOG",
style: new TextStyle(color: Colors.white),
),
centerTitle: true,
),
);
}
Demo