SRSensorReader
An object that establishes user authorization and records data for a particular sensor.
Declaration
class SRSensorReaderOverview
To acquire data from a particular sensor using a reader, an app creates an instance of this class using init(sensor:) and passes in one sensor from the available options in Sensors.
A reader is a data stream for a particular sensor that the user must authorize before use. When an app calls requestAuthorization(sensors:completion:), the OS prompts the user for approval to use the particular sensor and determines the app’s authorization according to the user’s answer. The framework notifies the delegate with the sensorReader(_:didChange:) callback if the authorization status changes as a result of the requestAuthorization(sensors:completion:) call. When a reader’s authorizationStatus is SRAuthorizationStatus.authorized, an app starts collecting sensor data by beginning recording.
When an app calls startRecording(), the framework starts the reader’s sensor if it isn’t already running because of a request from another app or a system process. An app has access to 7 days of prior recorded data for an active sensor. When an app calls stopRecording(), the app relinquishes stakeholdership in the sensor. When a sensor has no app or system stakeholders, the framework deactivates the sensor and, thereby, stops recording data.
To fetch a sensor’s data, pass a request object to the fetch(_:) function. SRFetchRequest specifies a time range that defines the age of the data, and a device, such as a phone or a watch, from which to collect the data. Use fetchDevices() to list the available devices, and use the time convenience-functions in Defining the Time Range to specify the time range.
If the fetch query succeeds, the framework notifies the delegate with sensorReader(_:didCompleteFetch:). The delegate receives sensor data in the form of samples from sensorReader(_:fetching:didFetchResult:). A fetch result’s sample type is different depending on the particular sensor for the reader. For a mapping of sensors to their samples, see Sample types.