---
title: "init(start:duration:)"
framework: foundation
role: symbol
role_heading: Initializer
path: "foundation/nsdateinterval/init(start:duration:)"
---

# init(start:duration:)

Initializes a date interval with a given start date and duration.

## Declaration

```swift
init(start startDate: Date, duration: TimeInterval)
```

## Parameters

- `startDate`: The start date of the date interval.
- `duration`: The duration from the start date for the date interval. important: This method raises an NSArgumentException if doc://com.apple.foundation/documentation/Foundation/NSDateInterval/duration is less than 0.

## Discussion

Discussion This is the designated initializer.

## See Also

### Creating Date Intervals

- [init()](foundation/nsdateinterval/init().md)
- [init(start:end:)](foundation/nsdateinterval/init(start:end:).md)
- [init(coder:)](foundation/nsdateinterval/init(coder:).md)