---
title: day()
framework: foundation
role: symbol
role_heading: Instance Method
path: foundation/date/iso8601formatstyle/day()
---

# day()

Modifies the ISO 8601 date format style to include the day in the formatted output.

## Declaration

```swift
func day() -> Date.ISO8601FormatStyle
```

## Return Value

Return Value An ISO 8601 date format style modified to include the day.

## Discussion

Discussion The following example shows an ISO 8601 format with, and without, a day. let meetingDate = Date() // Jun 23, 2021 at 12:51 PM meetingDate.formatted(.iso8601     .year()     .month() ) // 202106

meetingDate.formatted(.iso8601     .year()     .day() )  // 2021174

meetingDate.formatted(.iso8601     .year()     .month()     .day() )  // 20210623 If month() isn’t included in the format and day() is, the format represents the day as the ordinal date. The default Date.ISO8601FormatStyle includes the day. For more information about formatting dates, see the Date.FormatStyle.

## See Also

### Modifying Dates in an ISO 8601 Format Style

- [dateSeparator(_:)](foundation/date/iso8601formatstyle/dateseparator(_:).md)
- [year()](foundation/date/iso8601formatstyle/year().md)
- [month()](foundation/date/iso8601formatstyle/month().md)
- [weekOfYear()](foundation/date/iso8601formatstyle/weekofyear().md)