SonarFit Flutter Plugin

Official Flutter plugin for the SonarFit SDK - automatic rep counting from Apple Watch or AirPods Pro motion sensors.

pub package Platform

Features

  • Real-time Rep Detection: Motion-sensor analysis counts reps automatically
  • Multiple Exercise Support: Squats & deadlifts on AirPods; squats, deadlifts, bench press, shoulder press & bicep curls on Apple Watch
  • Device Flexibility: Works with Apple Watch or AirPods Pro
  • Built-in UI: Beautiful, ready-to-use workout interface
  • Progress Tracking: Automatic set/rep tracking with rest timers
  • Permission Handling: Automatic motion permission requests

Platform Support

Platform Support
iOS ✅ 17.0+
Android ❌ Not supported

Installation

Add this to your pubspec.yaml:

dependencies:
  sonarfit_flutter: ^2.4.1

Then run:

flutter pub get

iOS Configuration

  1. Update iOS deployment target in ios/Podfile:
platform :ios, '17.0'
  1. Add required permissions to ios/Runner/Info.plist:
<key>NSMotionUsageDescription</key>
<string>SonarFit needs motion sensor access to count your reps during workouts</string>

<key>NSHealthUpdateUsageDescription</key>
<string>SonarFit needs HealthKit access to save your workout data</string>

<key>NSHealthShareUsageDescription</key>
<string>SonarFit needs HealthKit access to read your workout history</string>
  1. Install CocoaPods dependencies:
cd ios && pod install && cd ..

Quick Start

1. Initialize the SDK

Get your API key from https://sonarfit.com/get-started

import 'package:sonarfit_flutter/sonarfit_flutter.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  // Initialize SonarFit SDK
  await SonarFit.initialize('your-api-key-here');

  runApp(MyApp());
}

2. Present a Workout

import 'package:flutter/material.dart';
import 'package:sonarfit_flutter/sonarfit_flutter.dart';

class WorkoutScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('SonarFit Workout')),
      body: Center(
        child: ElevatedButton(
          onPressed: () async {
            try {
              final result = await SonarFit.presentWorkout(
                WorkoutConfig(
                  workoutType: WorkoutType.squat,
                  sets: 3,
                  reps: 10,
                  deviceType: DeviceType.watch,
                  restTime: 60,
                ),
              );

              if (result.status == WorkoutStatus.completed) {
                print('Workout completed!');
                print('Reps: ${result.totalRepsCompleted}/${result.totalTargetReps}');
              } else {
                print('Workout stopped early');
                print('Reps: ${result.totalRepsCompleted}/${result.totalTargetReps}');
              }
            } on SonarFitException catch (e) {
              print('Error: ${e.message}');
            }
          },
          child: Text('Start Workout'),
        ),
      ),
    );
  }
}

API Reference

SonarFit

Main entry point for the SDK.

Methods

initialize(String apiKey)

Initialize the SDK with your API key. Must be called before using any other methods.

await SonarFit.initialize('your-api-key');

Throws: SonarFitException if initialization fails.

presentWorkout(WorkoutConfig config)

Present SonarFit's built-in workout UI.

final result = await SonarFit.presentWorkout(
  WorkoutConfig(
    workoutType: WorkoutType.squat,
    sets: 3,
    reps: 10,
    deviceType: DeviceType.watch,
    restTime: 60,
    countdownDuration: 3,
    autoReLift: true,
  ),
);

Returns: WorkoutResult when workout completes (either fully or stopped early).

Throws: SonarFitException if workout fails to start, permission is denied, or user cancels before starting.

WorkoutConfig

Configuration for a workout session.

Properties

Property Type Required Description
workoutType WorkoutType Yes Type of exercise
sets int Yes Number of sets
reps int Yes Target reps per set
deviceType DeviceType Yes Motion tracking device (.watch or .airpods)
restTime int No Rest duration in seconds
countdownDuration int No Countdown before each set
autoReLift bool No Auto-detect reps

Example

final config = WorkoutConfig(
  workoutType: WorkoutType.deadlift,
  sets: 5,
  reps: 5,
  deviceType: DeviceType.watch,
  restTime: 90,
  countdownDuration: 5,
  autoReLift: true,
);

WorkoutType

Supported exercise types.

enum WorkoutType {
  squat,          // AirPods or Apple Watch
  deadlift,       // AirPods or Apple Watch
  benchpress,     // Apple Watch only
  shoulderPress,  // Apple Watch only
  bicepCurl,      // Apple Watch only
}

DeviceType

Motion tracking devices.

enum DeviceType {
  watch,    // Apple Watch
  airpods,  // AirPods Pro/Max with motion sensors
}

Note: DeviceType.none exists for internal SDK use only. Clients must explicitly select either .watch or .airpods.

WorkoutStatus

Workout completion status.

enum WorkoutStatus {
  completed,      // All target sets finished
  stoppedEarly,   // User ended before completion
}

WorkoutResult

Result of a completed workout.

Properties

Property Type Description
workoutType WorkoutType Exercise type
deviceType DeviceType Device used for tracking
startTime DateTime Workout start time
endTime DateTime Workout end time
totalDuration double Total duration in seconds
status WorkoutStatus Workout completion status
completionPercentage double Completion percentage (0.0-1.0)
targetSets int Target number of sets
targetRepsPerSet int Target reps per set
totalRepsCompleted int Total reps completed
totalTargetReps int Total target reps
sets List<WorkoutSet> Per-set details

Example

print('Completed ${result.totalRepsCompleted}/${result.totalTargetReps} reps');
print('${(result.completionPercentage * 100).toStringAsFixed(0)}% complete');
print('Status: ${result.status}');

for (var set in result.sets) {
  print('Set ${set.setNumber}: ${set.repsCompleted} reps');
}

SonarFitException

Exception thrown by SDK operations.

Properties

Property Type Description
code String Error code
message String Human-readable error message
details dynamic Additional error details

Common Error Codes

Code Description
E_INIT_FAILED SDK initialization failed
E_PERMISSION Motion permission denied
E_INVALID_CONFIG Invalid workout configuration
E_NO_ROOT_VC Cannot find root view controller
E_CANCELLED Workout was cancelled by user
E_NO_RESULT Workout completed but no result was returned

Examples

Complete Workout Flow

import 'package:flutter/material.dart';
import 'package:sonarfit_flutter/sonarfit_flutter.dart';

class WorkoutExampleScreen extends StatefulWidget {
  @override
  _WorkoutExampleScreenState createState() => _WorkoutExampleScreenState();
}

class _WorkoutExampleScreenState extends State<WorkoutExampleScreen> {
  WorkoutResult? _lastResult;
  bool _isLoading = false;

  Future<void> _startWorkout() async {
    setState(() => _isLoading = true);

    try {
      final result = await SonarFit.presentWorkout(
        WorkoutConfig(
          workoutType: WorkoutType.squat,
          sets: 3,
          reps: 10,
          deviceType: DeviceType.watch,
          restTime: 60,
        ),
      );

      setState(() {
        _lastResult = result;
        _isLoading = false;
      });

      _showCompletionDialog(result);
    } on SonarFitException catch (e) {
      setState(() => _isLoading = false);
      _showErrorDialog(e);
    }
  }

  void _showCompletionDialog(WorkoutResult result) {
    final title = result.status == WorkoutStatus.completed
        ? 'Workout Complete!'
        : 'Workout Stopped';

    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: Text(title),
        content: Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text('Reps: ${result.totalRepsCompleted}/${result.totalTargetReps}'),
            Text('Completion: ${(result.completionPercentage * 100).toStringAsFixed(0)}%'),
            SizedBox(height: 16),
            Text('Sets:', style: TextStyle(fontWeight: FontWeight.bold)),
            ...result.sets.map((set) =>
              Text('Set ${set.setNumber}: ${set.repsCompleted} reps')),
          ],
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: Text('OK'),
          ),
        ],
      ),
    );
  }

  void _showErrorDialog(SonarFitException error) {
    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: Text('Error'),
        content: Text(error.message),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: Text('OK'),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('SonarFit Example')),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            if (_isLoading)
              CircularProgressIndicator()
            else
              ElevatedButton(
                onPressed: _startWorkout,
                child: Text('Start Workout'),
              ),
            if (_lastResult != null) ...[
              SizedBox(height: 32),
              Text(
                'Last Workout',
                style: Theme.of(context).textTheme.headlineSmall,
              ),
              SizedBox(height: 8),
              Text('${_lastResult!.totalRepsCompleted} reps completed'),
              Text('${(_lastResult!.completionPercentage * 100).toStringAsFixed(0)}% complete'),
            ],
          ],
        ),
      ),
    );
  }
}

Multiple Workout Types

class WorkoutTypeSelector extends StatelessWidget {
  final List<WorkoutType> workouts = [
    WorkoutType.squat,
    WorkoutType.deadlift,
    WorkoutType.benchpress,
    WorkoutType.shoulderPress,
    WorkoutType.bicepCurl,
  ];

  Future<void> _startWorkout(BuildContext context, WorkoutType type) async {
    try {
      final result = await SonarFit.presentWorkout(
        WorkoutConfig(
          workoutType: type,
          sets: 3,
          reps: 10,
          deviceType: DeviceType.watch,
        ),
      );

      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('${result.totalRepsCompleted} reps completed (${result.status.name})')),
      );
    } on SonarFitException catch (e) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('Error: ${e.message}')),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: workouts.length,
      itemBuilder: (context, index) {
        final workout = workouts[index];
        return ListTile(
          title: Text(_getWorkoutName(workout)),
          trailing: Icon(Icons.arrow_forward),
          onTap: () => _startWorkout(context, workout),
        );
      },
    );
  }

  String _getWorkoutName(WorkoutType type) {
    switch (type) {
      case WorkoutType.squat:
        return 'Squat';
      case WorkoutType.deadlift:
        return 'Deadlift';
      case WorkoutType.benchpress:
        return 'Bench Press';
    }
  }
}

Pricing

SonarFit uses MAU-based pricing (Monthly Active Users). A user counts as active when they complete at least one workout in a calendar month.

Tier Price Included MAUs Overage
Developer Free 500 (hard cap) N/A
Startup £129/mo 2,000 £0.08/MAU
Growth £599/mo 10,000 £0.07/MAU
Enterprise Custom Negotiated Custom

Get started at https://sonarfit.com/pricing

Requirements

  • Flutter: 3.3.0 or higher
  • Dart: 3.0.0 or higher
  • iOS: 17.0 or higher
  • Xcode: 16.0 or higher
  • CocoaPods: 1.11.0 or higher

Troubleshooting

Build Errors

Error: "Platform version is lower than 17.0"

Solution: Update ios/Podfile:

platform :ios, '17.0'

Error: "No such module 'SonarFitKit'"

Solution: Run:

cd ios && pod install && cd ..
flutter clean
flutter pub get

Runtime Errors

Error: "Motion permission denied"

Solution: Add NSMotionUsageDescription to Info.plist and ensure user grants permission when prompted.

Error: "SDK not initialized"

Solution: Call SonarFit.initialize() before using any other methods.

Support

License

MIT License - see LICENSE file for details

About SonarFit

SonarFit provides automatic rep counting for fitness apps. Our SDK handles real-time rep counting and workout progression so you can focus on building great user experiences.

Learn more at https://sonarfit.com

Native Watch app + Flutter phone app (headless watch detection)

If your Watch app is native Swift and counts reps with SonarFit inside its own UI (headless detection, see the SonarFit iOS integration guide), the Flutter phone app needs only:

await SonarFit.initialize('sk_live_...');   // licensing and usage metering of the watch's workouts

Optionally mirror the sets live in Flutter:

SonarFit.headlessEvents.listen((e) {
  switch (e.type) {
    case 'setStarted': /* e.exercise, e.targetReps, e.setIndex */ break;
    case 'rep':        /* e.count, cumulative */ break;
    case 'setEnded':   /* e.reps, e.duration, e.exercise */ break;
    case 'workoutEnded': /* e.setsCounted */ break;
  }
});

The Watch target links the SonarFit Swift package directly (SonarFitKit, watchOS 10+) and uses SonarFit.startHeadlessWorkout() / startRepDetection / endHeadlessWorkout(save:), or its own HKWorkoutSession with configureWatchSession(.hostProvided(...)). Requires SonarFit 2.6.0.

Libraries

sonarfit_flutter