# SRSensorReaderDelegate A set of callbacks the framework invokes to notify the app of sensor-related events. ``` protocol SRSensorReaderDelegate : NSObjectProtocol ``` ## Overview To access sensor data, assign an object as the delegate and implement its callbacks. ## Topics ### Checking Authorization Status [`func sensorReader(SRSensorReader, didChange: SRAuthorizationStatus)`](/documentation/SensorKit/SRSensorReaderDelegate/sensorReader(_:didChange:)) Notifies the delegate of the reader’s new authorization status. ### Fetching Devices [`func sensorReader(SRSensorReader, didFetch: [SRDevice])`](/documentation/SensorKit/SRSensorReaderDelegate/sensorReader(_:didFetch:)) Provides the delegate with one or more devices. [`func sensorReader(SRSensorReader, fetchDevicesDidFailWithError: any Error)`](/documentation/SensorKit/SRSensorReaderDelegate/sensorReader(_:fetchDevicesDidFailWithError:)) Provides the delegate a reason when the reader fails to fetch devices. [`class SRDevice`](/documentation/SensorKit/SRDevice) A representation of a device that provides sample data. ### Recording Data [`func sensorReaderWillStartRecording(SRSensorReader)`](/documentation/SensorKit/SRSensorReaderDelegate/sensorReaderWillStartRecording(_:)) Notifies the delegate when a reader starts recording. [`func sensorReader(SRSensorReader, startRecordingFailedWithError: any Error)`](/documentation/SensorKit/SRSensorReaderDelegate/sensorReader(_:startRecordingFailedWithError:)) Provides the delegate with a reason when the reader fails to record. [`func sensorReaderDidStopRecording(SRSensorReader)`](/documentation/SensorKit/SRSensorReaderDelegate/sensorReaderDidStopRecording(_:)) Notifies the delegate when a reader stops recording. [`func sensorReader(SRSensorReader, stopRecordingFailedWithError: any Error)`](/documentation/SensorKit/SRSensorReaderDelegate/sensorReader(_:stopRecordingFailedWithError:)) Provides the delegate with a reason when the reader fails to stop recording. ### Reading Recorded Data [`func sensorReader(SRSensorReader, fetching: SRFetchRequest, didFetchResult: SRFetchResult) -> Bool`](/documentation/SensorKit/SRSensorReaderDelegate/sensorReader(_:fetching:didFetchResult:)) Provides the delegate with a fetch result. [`func sensorReader(SRSensorReader, didCompleteFetch: SRFetchRequest)`](/documentation/SensorKit/SRSensorReaderDelegate/sensorReader(_:didCompleteFetch:)) Provides the delegate with a completed fetch request. [`func sensorReader(SRSensorReader, fetching: SRFetchRequest, failedWithError: any Error)`](/documentation/SensorKit/SRSensorReaderDelegate/sensorReader(_:fetching:failedWithError:)) Provides the delegate with a fetch failure reason. ### Interpreting Errors [`let SRErrorDomain: String`](/documentation/SensorKit/SRErrorDomain) An error domain that’s unique to the framework. [`struct SRError`](/documentation/SensorKit/SRError) An error that SensorKit reports. [`enum Code`](/documentation/SensorKit/SRError/Code) The kinds of problems that stop a recording or a fetch. ## Relationships ### Inherits From [`NSObjectProtocol`](/documentation/ObjectiveC/NSObjectProtocol) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)