---
title: "CMBatchedSensorManager: high-frequency motion batches during workouts"
canonical: "https://aifitnessapi.com/phone-sensors/cmbatchedsensormanager"
cluster: "Phone Sensors"
primary_query: "CMBatchedSensorManager"
last_reviewed: "2026-10-03"
description: "What Apple documents about CMBatchedSensorManager: batched accelerometer and device motion during workouts, watchOS 10.0, and what it leaves out."
publisher: "AIFitnessAPI — independent, not sponsored"
cite_as: "\"CMBatchedSensorManager: high-frequency motion batches during workouts\", AIFitnessAPI, https://aifitnessapi.com/phone-sensors/cmbatchedsensormanager"
---

# CMBatchedSensorManager: high-frequency motion batches during workouts

> CMBatchedSensorManager is the Core Motion class Apple introduced, per its June 2023 update notes, to access batches of high-frequency accelerometer and device motion data during workouts, such as a golf swing or a baseball bat swing. It delivers arrays of CMAccelerometerData or CMDeviceMotion samples through start methods with handlers, plus async sequences that Apple lists for watchOS 10.0 only. The class page carries no overview text, no documented sample rate and no statement about whether a workout session must be running, so those details could not be verified from Apple's documentation. Its class-level iOS stamp of 4.0 is the same number Apple gives the Core Motion framework itself, so do not read it as an iPhone introduction date.

- Canonical: https://aifitnessapi.com/phone-sensors/cmbatchedsensormanager
- Last reviewed: 2026-10-03
- Publisher: AIFitnessAPI (https://aifitnessapi.com) — independent, not sponsored
- Cite as: "CMBatchedSensorManager: high-frequency motion batches during workouts", AIFitnessAPI, https://aifitnessapi.com/phone-sensors/cmbatchedsensormanager

---

This is the class for swing analysis, punch detection and other movements that happen faster than ordinary motion updates capture. It is also one of the thinnest pages in Apple's Core Motion documentation. Here is what Apple says, read on 2026-10-03, and where it stops.

## What Apple says it is for

The [CMBatchedSensorManager page](https://developer.apple.com/documentation/coremotion/cmbatchedsensormanager) has no overview. The purpose is stated on the [Core Motion updates](https://developer.apple.com/documentation/updates/coremotion) page, under June 2023: "Use the CMBatchedSensorManager class to access batches of high-frequency accelerometer and device motion data during workouts, such as a golf swing or a baseball bat swing." Apple's processed device-motion article also lists it as one of three device-motion providers, next to `CMMotionManager` and `CMHeadphoneMotionManager`. On the Core Motion index the class sits alone under a topic named "Historical data".

## The API surface

Apple's member list, none of which carries a description:

| Group | Members |
| --- | --- |
| Authorization and support | `authorizationStatus`, `isAccelerometerSupported`, `isDeviceMotionSupported` (class properties) |
| Frequency | `accelerometerDataFrequency`, `deviceMotionDataFrequency` (read-only `Int`) |
| Accelerometer | `startAccelerometerUpdates()`, `startAccelerometerUpdates(handler:)`, `stopAccelerometerUpdates()`, `accelerometerBatch`, `accelerometerUpdates()`, `isAccelerometerActive` |
| Device motion | `startDeviceMotionUpdates()`, `startDeviceMotionUpdates(handler:)`, `stopDeviceMotionUpdates()`, `deviceMotionBatch`, `deviceMotionUpdates()`, `isDeviceMotionActive` |

The handler forms take arrays: `([CMAccelerometerData]?, (any Error)?) -> Void` and `([CMDeviceMotion]?, (any Error)?) -> Void`. A batch is many samples per callback, which is the point of the class.

## Platforms, and a misleading number

Apple's page lists watchOS 10.0. It also lists iOS and iPadOS 4.0, Mac Catalyst 13.0 and visionOS 1.0. The iOS figure is the same 4.0 Apple gives the whole Core Motion framework, while Apple's update notes announce the class in June 2023. We read that stamp as inherited from the framework rather than as the class's history, and we could not find an Apple page that states an iPhone introduction version. The async-sequence accessors `accelerometerUpdates()` and `deviceMotionUpdates()` list watchOS 10.0 and nothing else.

## A minimal sketch

```swift
import CoreMotion

let batched = CMBatchedSensorManager()

func startSwingCapture(onBatch: @escaping ([CMAccelerometerData]) -> Void) {
    guard CMBatchedSensorManager.isAccelerometerSupported else { return }
    // accelerometerDataFrequency reports the rate; Apple does not document its value.
    batched.startAccelerometerUpdates { samples, error in
        guard let samples, error == nil else { return }
        onBatch(samples)            // many samples per callback; each carries a timestamp
    }
}

func stopSwingCapture() { batched.stopAccelerometerUpdates() }
```

Each `CMAccelerometerData` inherits a `timestamp` from `CMLogItem`, which Apple describes as recording "when the acceleration measurement was taken". Order and window your analysis on those timestamps, not on callback arrival.

We do not show the async-sequence form. Apple documents that `AccelerometerUpdates` conforms to `AsyncSequence`, but its element type and iterator carry no description we could read, and a sketch that guesses the element type is a sketch that may not compile.

## What we could not verify

- **The sample rate.** `accelerometerDataFrequency` and `deviceMotionDataFrequency` exist; their values are not documented. Read them at runtime.
- **Whether a workout session is required.** Apple's note says "during workouts". The class page does not say whether an `HKWorkoutSession` must be active, and we will not claim it either way. How a watch workout session works is on [the anatomy of a watchOS workout app](/watch-apps/watchos-workout-app-anatomy).
- **Battery cost and batch size.** Not documented.
- **Permission specifics.** `authorizationStatus` returns a `CMAuthorizationStatus`. Apple's Core Motion overview says an iOS app needs `NSMotionUsageDescription` "To access motion and fitness data"; the batched page itself says nothing about permissions.

## Pitfalls

- **Treating the iOS 4.0 stamp as the class's history.** It matches the framework's number.
- **Expecting one sample per callback.** Handlers receive arrays.
- **Hard-coding a frequency.** Read the frequency properties; no value is published.
- **Leaving capture running.** Start for the swing window, stop after. The power cost of high-rate motion is real even where Apple does not quantify it; see [watch app battery](/watch-apps/watch-app-battery).
- **Assuming the class counts anything.** It hands you samples. Turning them into swings or reps is your model; [how rep counting works](/motion/how-rep-counting-works) covers the patterns.

## FAQ

### Is CMBatchedSensorManager available on iPhone?

Apple's documentation does not say clearly. The class page lists watchOS 10.0, and also lists iOS and iPadOS 4.0, which is the same version Apple gives the entire Core Motion framework; the class itself was announced in Apple's June 2023 Core Motion update notes, so we do not read the 4.0 figure as its iPhone introduction. The async-sequence accessors are listed for watchOS 10.0 only. Check isAccelerometerSupported and isDeviceMotionSupported at runtime rather than trusting the platform stamp.

[Permalink](https://aifitnessapi.com/phone-sensors/cmbatchedsensormanager#faq-1)

### What sampling rate does CMBatchedSensorManager deliver?

Apple does not publish one. The class exposes accelerometerDataFrequency and deviceMotionDataFrequency as read-only integers, but their documentation pages have no description and no value. Apple's update note says only that the class provides high-frequency accelerometer and device motion data. Read the frequency properties on the device at runtime, and use each sample's timestamp rather than an assumed rate when you window the data.

[Permalink](https://aifitnessapi.com/phone-sensors/cmbatchedsensormanager#faq-2)

### Does CMBatchedSensorManager need an active workout session?

Could not verify. Apple's Core Motion update note describes the class as giving access to high-frequency data during workouts, with a golf swing or baseball bat swing as examples, but the CMBatchedSensorManager page itself contains no discussion and does not state whether a workout session has to be running. Test the behaviour on a device with and without your workout session active before building a feature that depends on either answer.

[Permalink](https://aifitnessapi.com/phone-sensors/cmbatchedsensormanager#faq-3)

### Why does CMBatchedSensorManager deliver arrays instead of single samples?

Because batching is its job. The handler for startAccelerometerUpdates(handler:) receives an optional array of CMAccelerometerData, and the device-motion handler an optional array of CMDeviceMotion. Apple's update note calls them batches of high-frequency data. Process each callback as a block of samples ordered by their timestamps, rather than treating the callback as one reading.

[Permalink](https://aifitnessapi.com/phone-sensors/cmbatchedsensormanager#faq-4)