---
title: "appendInterpolation(dayPeriod:)"
framework: foundation
role: symbol
role_heading: Instance Method
path: "foundation/date/formatstring/stringinterpolation/appendinterpolation(dayperiod:)"
---

# appendInterpolation(dayPeriod:)

## Declaration

```swift
mutating func appendInterpolation(dayPeriod: Date.FormatStyle.Symbol.DayPeriod)
```