---
title: "+=(_:_:)"
framework: foundation
role: symbol
role_heading: Operator
path: "foundation/date/+=(_:_:)"
---

# +=(_:_:)

Adds a time interval to a date.

## Declaration

```swift
static func += (lhs: inout Date, rhs: TimeInterval)
```

## Parameters

- `lhs`: A date.
- `rhs`: A doc://com.apple.foundation/documentation/Foundation/TimeInterval to add to the date.

## Discussion

Discussion warning: This only adjusts an absolute value. If you wish to add calendrical concepts like hours, days, months then you must use a Calendar. This takes into account complexities like daylight saving time, months with different numbers of days, and more.

## See Also

### Adding or Subtracting a Time Interval

- [addTimeInterval(_:)](foundation/date/addtimeinterval(_:).md)
- [addingTimeInterval(_:)](foundation/date/addingtimeinterval(_:).md)
- [advanced(by:)](foundation/date/advanced(by:).md)
- [+(_:_:)](foundation/date/+(_:_:).md)
- [-(_:_:)](foundation/date/-(_:_:).md)
- [-=(_:_:)](foundation/date/-=(_:_:).md)