Flutter

问题 Below code always show OnboardingScreen a little time (maybe miliseconds), after that display MyHomePage. I am sure that you all understand what i try to do. I am using FutureBuilder to check getString method has data. Whats my fault ? Or any other best way for this ? saveString() async { final prefs = await SharedPreferences.getInstance(); prefs.setString('firstOpen', '1'); } getString() method always return string. getString() async { final prefs = await SharedPreferences.getInstance();

问题 Is it possible to open the contacts on a device from an icon tap in flutter? I am able to open the phone function using url_launcher's plugin.I have used the contacts plugin but we dont have a need to manage contacts from our application, we want to use the phones functionality for managing contacts. 回答1: You can achieve this using Flutter platform channels and android Intent.ACTION_VIEW intent. For example in your MainActivity register new channel and launch Contacts activity: MethodChannel

问题 Is there a way to load images in Flutter in a function without access to a BuildContext? Flutter can preload images with precacheImage() which requires a BuildContext and is inconvenient to use. I would like to load images in the initState() method of a StatefulWidget which precacheImage() does not support. There is an open issue about preloading images that suggests loading images without a BuildContext is not currently supported. https://github.com/flutter/flutter/issues/26127 回答1: I know

问题 I have two BLoCs. EstateBloc EstateTryBloc My Application basically gets estates from an API and displays them in a similar fashion Now I wanted to add a sort functionality, but I could only access the List of Estates via a specific state. if(currentState is PostLoadedState){{ print(currentState.estates); } I wanted to make the List of estates available for whichever bloc, that needed that list. What I did was, I created the EstateTryBloc, which basically contains the List of estates as a

问题 See the issue at https://dartpad.dev/c8fc4e640c882616c372653c92362b17 The Datepicker is opening and setting the date in the state, but the selected date is not visible in the TextFormField. Any solution? 回答1: You can copy paste run full code below You can in onTap await _selectDate(context); and set date string with TextEditingController() code snippet TextEditingController _textEditingController = TextEditingController(); Widget buildDateField() { return TextFormField( controller:

问题 Transaction is an atomic process but that means we need to read the data prior to incrementing it. We can easily implement ServerValue.increment(1) in Node.js but in Flutter we only have ServerValue.timestamp according to the documentation here although the Google documentation has it And so far I search I haven't found anything yet. Am I missing something? 来源： https://stackoverflow.com/questions/63275901/does-realtime-database-has-atomic-increment-method-for-flutter-like-servervalue

问题 I created a mobile application with flutter in front end and back end with node.js but I want it to use node js in offline mode in another meaning I want host this node inside the mobile. can I? 回答1: No. First, you'd need NodeJS itself built for you mobile platform. Only then can you even consider running the node application you've written. Flutter is Dart and NodeJS is well, JS. You can't put them together. But if you are building a node app that builds into a static js and html, may be you

问题 I have two streams: Stream<List<Order>> stream1 = pendingStream(); Stream<List<Order>> stream2 = preparingStream(); I'm trying to use StreamZip from the package:async/async.dart package to merge the streams like so... Stream<List<Order>> getData() { Stream<List<Order>> stream1 = pendingStream(); Stream<List<Order>> stream2 = preparingStream(); return StreamZip([stream1, stream2]); } However it won't compile. Saying: The element type 'Stream<List<Order>>' can't be assigned to the list type

问题 I'm trying to find how to fade between PageView pages. This is my pageView: PageView( controller: controller, children: [ Container( decoration: BoxDecoration( image: DecorationImage( image: AssetImage("assets/image4.jpg"), fit: BoxFit.cover), ), child: Center( child: Text( 'myText', style: TextStyle(color: Colors.white, fontSize: 40.0), )), ), Container( decoration: BoxDecoration( image: DecorationImage( image: AssetImage("assets/image2.jpg"), fit: BoxFit.cover), ), child: Center( child:

问题 I am using below code to regenerate my Json using PowerShell, however it creates unexpected character before the start of the json { tag. <#$data = Get-Content -Raw -Path myfile.json | ConvertFrom-Json#> $data = @" { "stations": [ { "code": "1", "name": "United force" }, { "code": "2", "name": "Toowoon Bay Service Station" } ], "prices": [ { "stationcode": "1", "fueltype": "DL", "price": 126.97 }, { "stationcode": "1", "fueltype": "E10", "price": 118.92 }, { "stationcode": "2", "fueltype":