对于在iOS和Android上略有不同的UI,即在不同的平台上,必须有一种方法来检测应用程序在哪个平台上运行,但我在文档中找不到它。是什么?
对于在iOS和Android上略有不同的UI,即在不同的平台上,必须有一种方法来检测应用程序在哪个平台上运行,但我在文档中找不到它。是什么?
我用TextFormField收集用户输入,当用户按下FloatingActionButton表示他们已经完成时,我想解散屏幕上的键盘。
如何让键盘自动消失?
import 'package:flutter/material.dart';
class MyHomePage extends StatefulWidget {
MyHomePageState createState() => new MyHomePageState();
}
class MyHomePageState extends State<MyHomePage> {
TextEditingController _controller = new TextEditingController();
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(),
floatingActionButton: new FloatingActionButton(
child: new Icon(Icons.send),
onPressed: () {
setState(() {
// send message
// dismiss on screen keyboard here
_controller.clear();
});
},
),
body: new Container(
alignment: FractionalOffset.center,
padding: new EdgeInsets.all(20.0),
child: new TextFormField(
controller: _controller,
decoration: new InputDecoration(labelText: 'Example Text'),
),
),
);
}
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
home: new MyHomePage(),
);
}
}
void main() {
runApp(new MyApp());
}
是否有办法更改Flutter项目的Package Name ?
我想在flutter项目中更改包名和应用名。
在Dart中,const和final关键字之间有什么区别?
我正在构建一个Flutter应用程序,我已经集成了Firebase,但当我点击一个按钮注册,登录或注销时,我一直得到这个错误。我看到其他人也问过同样的问题,但似乎没有一个对我有用。我正在使用Flutter和Android Studio。我该如何解决这个问题?
这是我的代码的摘录
class HomeScreen extends StatefulWidget {
@override
_HomeScreenState createState() => _HomeScreenState();
}
class _HomeScreenState extends State<HomeScreen> {
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.red,
body: Center(
child: Container(
child: RaisedButton(
onPressed: () {
FirebaseAuth.instance.signOut().then((value) {
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (context) =>
LoginScreen()));
});
},
child: Text("Logout"),
)
)
)
);
}
}
下面是抛出的异常
══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════
The following FirebaseException was thrown while handling a gesture:
[core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()
When the exception was thrown, this was the stack:
#0 MethodChannelFirebase.app (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:118:5)
#1 Firebase.app (package:firebase_core/src/firebase.dart:52:41)
#2 FirebaseAuth.instance (package:firebase_auth/src/firebase_auth.dart:37:47)
#3 _HomeScreenState.build.<anonymous closure> (package:cosytok/screens/home.dart:20:28)
#4 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:992:19)
#5 _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:1098:38)
#6 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:184:24)
#7 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:524:11)
#8 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:284:5)
#9 BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:219:7)
#10 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:477:9)
#11 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:78:12)
#12 PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:124:9)
#13 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8)
#14 PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:122:18)
#15 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:108:7)
#16 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:220:19)
#17 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:200:22)
#18 GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:158:7)
#19 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:104:7)
#20 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:88:7)
#24 _invoke1 (dart:ui/hooks.dart:267:10)
#25 _dispatchPointerDataPacket (dart:ui/hooks.dart:176:5)
(elided 3 frames from dart:async)
Handler: "onTap"
Recognizer:
TapGestureRecognizer#f0104
════════════════════════════════════════════════════════════════════════════════════════════════════
════════ Exception caught by gesture ═══════════════════════════════════════════════════════════════
The following FirebaseException was thrown while handling a gesture:
[core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()
单例模式确保只创建一个类的实例。我如何在达特建立这个?
我正在使用Flutter,我想向小部件(在本例中是文本小部件)添加边框。
我尝试了TextStyle和文本,但我不知道如何添加边框。
当我使用flutter create命令创建应用程序时,flutter标志将用作两个平台的应用程序图标。
如果我想改变应用程序的图标,我是否应该去两个平台的目录并替换那里的图像?我说的平台目录是myapp/ios/Runner/Assets.xcassets/AppIcon。apppiconset用于iOS, myapp/android/app/src/main/res用于android。
或者可以将图像定义为颤振资产和图标以某种方式生成?
我目前正在Flutter开发一个Android应用程序。我如何添加一个圆形按钮?