Step 4: Collect

What you’ll do: start data collection and show each measurement as it arrives.

Steps

1. Replace lib/main.dart with this. It runs Step 3 and then starts collecting:

   lib/main.dart

   import 'package:flutter/material.dart';
   import 'package:carp_mobile_sensing/carp_mobile_sensing.dart';
   import 'protocol.dart';
   
   void main() => runApp(const MaterialApp(home: StepsPage()));
   
   class StepsPage extends StatefulWidget {
     const StepsPage({super.key});
     @override
     State<StepsPage> createState() => _StepsPageState();
   }
   
   class _StepsPageState extends State<StepsPage> {
     final List<String> _log = [];
   
     @override
     void initState() {
       super.initState();
       _start();
     }
   
     Future<void> _start() async {
       // Step 3: deploy
       final client = SmartPhoneClientManager();
       await client.configure();
       final study = await client.addStudyFromProtocol(createProtocol());
       await client.tryDeployment(study.studyDeploymentId, study.deviceRoleName);
   
       // Step 4: collect
       client.resume();
       client.measurements.listen((m) => setState(() => _log.insert(0, m.data.dataType.name)));
     }
   
     @override
     Widget build(BuildContext context) => Scaffold(
           appBar: AppBar(title: const Text('My first CARP app')),
           body: ListView(children: [for (final line in _log) ListTile(title: Text(line))]),
         );
   }

   resume() presses play. measurements is a live stream of everything collected.

2. Run it.

   flutter run

   Tap Allow when the app asks for permissions (notifications, physical activity).

Check it works

Walk around. stepevent and batterystate appear in the list. Every measurement is also saved in the database on the phone.

Collect more kinds of data

Add a sampling package or a wearable. For example, location and activity:

flutter pub add carp_context_package

SamplingPackageRegistry().register(ContextSamplingPackage()); // before creating the protocol
Measure(type: ContextSamplingPackage.LOCATION),               // in the protocol

All available measures: Measure types. To keep collecting when the app is closed, see Run in production.

Next: Step 5: Get the data