---
title: "init(healthStore:device:start:)"
framework: healthkit
role: symbol
role_heading: Initializer
path: "healthkit/hkheartbeatseriesbuilder/init(healthstore:device:start:)"
---

# init(healthStore:device:start:)

Creates a new heartbeat series builder.

## Declaration

```swift
init(healthStore: HKHealthStore, device: HKDevice?, start startDate: Date)
```

## Parameters

- `healthStore`: The HealthKit store.
- `device`: An object representing the device that provided the heartbeat data. Pass nil if the app is generating its own data.
- `startDate`: The sample’s start date.

## See Also

### Creating a Heartbeat Series Builder

- [maximumCount](healthkit/hkheartbeatseriesbuilder/maximumcount.md)