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

# appendInterpolation(weekday:)

## Declaration

```swift
mutating func appendInterpolation(weekday: Date.FormatStyle.Symbol.Weekday)
```