---
title: formatOptions
framework: foundation
role: symbol
role_heading: Instance Property
path: foundation/iso8601dateformatter/formatoptions
---

# formatOptions

Options for generating and parsing ISO 8601 date representations. See ISO8601DateFormatter.Options for possible values.

## Declaration

```swift
var formatOptions: ISO8601DateFormatter.Options { get set }
```

## Discussion

Discussion The ISO 8601 specification allows for dates to be expressed in a variety of ways. You can configure the format used to parse and generate representations by specifying various combinations of format options.  |  |   |  |   |  |   |  |   |  |   |  |   |  |  important: Resetting this property can incur a significant performance cost, as it may cause internal state to be regenerated.

## See Also

### Configuring the Formatter

- [timeZone](foundation/iso8601dateformatter/timezone.md)