SensorKit

<key>com.apple.developer.sensorkit.reader.allow</key>
<array>
    <string>ambient-light-sensor</string>
    <string>motion-accelerometer</string>
    <string>motion-rotation-rate</string>
    <string>device-usage</string>
    <string>keyboard-metrics</string>
    <string>messages-usage</string>
    <string>phone-usage</string>
    <string>visits</string>
    <string>pedometer</string>
    <string>on-wrist</string>
    <string>speech-metrics-siri</string>
    <string>speech-metrics-telephony</string>
    <string>ambient-pressure</string>
    <string>ecg</string>
    <string>ppg</string>
</array>

<!-- Study purpose shown in the authorization sheet -->
<key>NSSensorKitUsageDescription</key>
<string>This study monitors activity patterns for sleep research.</string>

<!-- Link to your study's privacy policy -->
<key>NSSensorKitPrivacyPolicyURL</key>
<string>https://example.com/privacy-policy</string>

<!-- Per-sensor usage explanations -->
<key>NSSensorKitUsageDetail</key>
<dict>
    <key>SRSensorUsageMotion</key>
    <dict>
        <key>Description</key>
        <string>Measures physical activity levels during the study.</string>
        <key>Required</key>
        <true/>
    </dict>
    <key>SRSensorUsageAmbientLightSensor</key>
    <dict>
        <key>Description</key>
        <string>Records ambient light to assess sleep environment.</string>
    </dict>
</dict>

import SensorKit

let reader = SRSensorReader(sensor: .ambientLightSensor)

// Request authorization for multiple sensors at once
SRSensorReader.requestAuthorization(
    sensors: [.ambientLightSensor, .accelerometer, .keyboardMetrics]
) { error in
    if let error {
        print("Authorization request failed: \(error)")
    }
}

switch reader.authorizationStatus {
case .authorized:
    reader.startRecording()
case .denied:
    // User declined -- direct to Settings > Privacy > Research Sensor & Usage Data
    break
case .notDetermined:
    // Request authorization first
    break
@unknown default:
    break
}

func sensorReader(_ reader: SRSensorReader, didChange authorizationStatus: SRAuthorizationStatus) {
    switch authorizationStatus {
    case .authorized:
        reader.startRecording()
    case .denied:
        reader.stopRecording()
    default:
        break
    }
}

import SensorKit

// Create a reader for one sensor
let lightReader = SRSensorReader(sensor: .ambientLightSensor)
let keyboardReader = SRSensorReader(sensor: .keyboardMetrics)

// Assign delegate to receive callbacks
lightReader.delegate = self
keyboardReader.delegate = self

// Begin recording -- sensor stays active as long as any app has a stake
reader.startRecording()

// Stop recording -- framework deactivates the sensor when
// no app or system process is using it
reader.stopRecording()

let request = SRFetchRequest()
request.device = SRDevice.current
request.from = SRAbsoluteTime(CFAbsoluteTimeGetCurrent() - 86400 * 2)  // 2 days ago
request.to = SRAbsoluteTime.current()

reader.fetch(request)

func sensorReader(
    _ reader: SRSensorReader,
    fetching request: SRFetchRequest,
    didFetchResult result: SRFetchResult<AnyObject>
) -> Bool {
    let timestamp = result.timestamp

    switch reader.sensor {
    case .ambientLightSensor:
        if let sample = result.sample as? SRAmbientLightSample {
            let lux = sample.lux
            let chromaticity = sample.chromaticity
            let placement = sample.placement
            processSample(lux: lux, chromaticity: chromaticity, at: timestamp)
        }
    case .keyboardMetrics:
        if let sample = result.sample as? SRKeyboardMetrics {
            let words = sample.totalWords
            let speed = sample.typingSpeed
            processKeyboard(words: words, speed: speed, at: timestamp)
        }
    case .deviceUsageReport:
        if let sample = result.sample as? SRDeviceUsageReport {
            let wakes = sample.totalScreenWakes
            let unlocks = sample.totalUnlocks
            processUsage(wakes: wakes, unlocks: unlocks, at: timestamp)
        }
    default:
        break
    }

    return true  // Return true to continue receiving results
}

func sensorReader(_ reader: SRSensorReader, didCompleteFetch request: SRFetchRequest) {
    print("Fetch complete for \(reader.sensor)")
}

func sensorReader(
    _ reader: SRSensorReader,
    fetching request: SRFetchRequest,
    failedWithError error: any Error
) {
    print("Fetch failed: \(error)")
}

// Get the current device
let currentDevice = SRDevice.current
print("Model: \(currentDevice.model)")
print("System: \(currentDevice.systemName) \(currentDevice.systemVersion)")

// Fetch all available devices for a sensor
reader.fetchDevices()

func sensorReader(_ reader: SRSensorReader, didFetch devices: [SRDevice]) {
    for device in devices {
        let request = SRFetchRequest()
        request.device = device
        request.from = SRAbsoluteTime(CFAbsoluteTimeGetCurrent() - 86400)
        request.to = SRAbsoluteTime.current()
        reader.fetch(request)
    }
}

func sensorReader(_ reader: SRSensorReader, fetchDevicesDidFailWithError error: any Error) {
    print("Failed to fetch devices: \(error)")
}

// WRONG -- fails at runtime with SRError.invalidEntitlement
let reader = SRSensorReader(sensor: .ambientLightSensor)
reader.startRecording()

// CORRECT -- obtain entitlement from Apple first, configure manual
// provisioning profile, then use SensorKit

// WRONG -- fetching data recorded moments ago returns nothing
reader.startRecording()
// ... record for a few minutes ...
let request = SRFetchRequest()
request.from = SRAbsoluteTime(CFAbsoluteTimeGetCurrent() - 300)
request.to = SRAbsoluteTime.current()
reader.fetch(request)  // Empty results due to 24-hour hold

// CORRECT -- fetch data that is at least 24 hours old
request.from = SRAbsoluteTime(CFAbsoluteTimeGetCurrent() - 86400 * 3)
request.to = SRAbsoluteTime(CFAbsoluteTimeGetCurrent() - 86400)
reader.fetch(request)

// WRONG -- no delegate means no callbacks, results are silently lost
let reader = SRSensorReader(sensor: .accelerometer)
reader.startRecording()
reader.fetch(request)

// CORRECT -- assign delegate first
reader.delegate = self
reader.startRecording()
reader.fetch(request)

// WRONG -- missing NSSensorKitUsageDetail for the sensor
// Authorization sheet shows no explanation, user is less likely to approve

// CORRECT -- add usage detail for every sensor you request
// See Info.plist Configuration section above

// WRONG -- generic error handling
func sensorReader(_ reader: SRSensorReader, fetching: SRFetchRequest, failedWithError error: any Error) {
    print("Error")
}

// CORRECT -- handle specific error codes
func sensorReader(_ reader: SRSensorReader, fetching: SRFetchRequest, failedWithError error: any Error) {
    if let srError = error as? SRError {
        switch srError.code {
        case .invalidEntitlement:
            // Entitlement missing or sensor not in entitlement array
            break
        case .noAuthorization:
            // User has not authorized this sensor
            break
        case .dataInaccessible:
            // Data in 24-hour holding period or otherwise unavailable
            break
        case .fetchRequestInvalid:
            // Invalid time range or device
            break
        case .promptDeclined:
            // User declined the authorization prompt
            break
        @unknown default:
            break
        }
    }
}