---
title: "init(timeIntervalSinceReferenceDate:)"
framework: foundation
role: symbol
role_heading: Initializer
path: "foundation/nsdate/init(timeintervalsincereferencedate:)"
---

# init(timeIntervalSinceReferenceDate:)

Returns a date object initialized relative to 00:00:00 UTC on 1 January 2001 by a given number of seconds.

## Declaration

```swift
init(timeIntervalSinceReferenceDate ti: TimeInterval)
```

## Parameters

- `ti`: The number of seconds to add to the reference date (00:00:00 UTC on 1 January 2001). A negative value means the receiver will be earlier than the reference date.

## Return Value

Return Value An NSDate object initialized relative to the absolute reference date by ti seconds.

## Discussion

Discussion This method is a designated initializer for the NSDate class and is declared primarily for the use of subclasses of NSDate. When you subclass NSDate to create a concrete date class, you must override this method.

## See Also

### Initializing a Date

- [init()](foundation/nsdate/init().md)
- [init(timeIntervalSinceNow:)](foundation/nsdate/init(timeintervalsincenow:).md)
- [init(timeIntervalSince1970:)](foundation/nsdate/init(timeintervalsince1970:).md)
- [init(coder:)](foundation/nsdate/init(coder:).md)