<!--
{
  "availability" : [
    "iOS: 2.0.0 -",
    "iPadOS: 2.0.0 -",
    "macCatalyst: 13.0.0 -",
    "macOS: 10.0.0 -",
    "tvOS: 9.0.0 -",
    "visionOS: 1.0.0 -",
    "watchOS: 2.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "Foundation",
  "identifier" : "/documentation/Foundation/NSDate/init(timeIntervalSinceReferenceDate:)",
  "metadataVersion" : "0.1.0",
  "role" : "Initializer",
  "symbol" : {
    "kind" : "Initializer",
    "modules" : [
      "Foundation"
    ],
    "preciseIdentifier" : "c:objc(cs)NSDate(im)initWithTimeIntervalSinceReferenceDate:"
  },
  "title" : "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.

```
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

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

## 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

[`dateWithTimeIntervalSinceReferenceDate:`](/documentation/Foundation/NSDate/dateWithTimeIntervalSinceReferenceDate:)

Creates and returns a date object set to a given number of seconds from 00:00:00 UTC on 1 January 2001.


---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)