---
title: rollingStartNumber
framework: exposurenotification
role: symbol
role_heading: Instance Property
path: exposurenotification/entemporaryexposurekey/rollingstartnumber
---

# rollingStartNumber

A number that indicates when a key’s rolling period started.

## Declaration

```swift
var rollingStartNumber: ENIntervalNumber { get set }
```

## Discussion

Discussion important: This property is available in iOS 12.5, and in iOS 13.5 and later.

## See Also

### Exposure Criteria

- [transmissionRiskLevel](exposurenotification/entemporaryexposurekey/transmissionrisklevel.md)
- [rollingPeriod](exposurenotification/entemporaryexposurekey/rollingperiod.md)
- [keyData](exposurenotification/entemporaryexposurekey/keydata.md)
- [ENIntervalNumber](exposurenotification/enintervalnumber.md)