---
title: "appendInterpolation(_:specifier:)"
framework: swiftui
role: symbol
role_heading: Instance Method
path: "swiftui/localizedstringkey/stringinterpolation/appendinterpolation(_:specifier:)"
---

# appendInterpolation(_:specifier:)

Appends a type, convertible to a string with a format specifier, to a string interpolation.

## Declaration

```swift
mutating func appendInterpolation<T>(_ value: T, specifier: String) where T : _FormatSpecifiable
```

## Parameters

- `value`: The value to append.
- `specifier`: A format specifier to convert subject to a string representation, like %f for a doc://com.apple.documentation/documentation/Swift/Double, or %x to create a hexidecimal representation of a doc://com.apple.documentation/documentation/Swift/UInt32. For a list of available specifier strings, see https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFStrings/formatSpecifiers.html#//apple_ref/doc/uid/TP40004265.

## Discussion

Discussion Don’t call this method directly; it’s used by the compiler when interpreting string interpolations.

## See Also

### Appending to an interpolation

- [appendInterpolation(_:)](swiftui/localizedstringkey/stringinterpolation/appendinterpolation(_:).md)
- [appendInterpolation(_:format:)](swiftui/localizedstringkey/stringinterpolation/appendinterpolation(_:format:).md)
- [appendInterpolation(_:formatter:)](swiftui/localizedstringkey/stringinterpolation/appendinterpolation(_:formatter:).md)
- [appendInterpolation(_:style:)](swiftui/localizedstringkey/stringinterpolation/appendinterpolation(_:style:).md)
- [appendInterpolation(timerInterval:pauseTime:countsDown:showsHours:)](swiftui/localizedstringkey/stringinterpolation/appendinterpolation(timerinterval:pausetime:countsdown:showshours:).md)
- [appendLiteral(_:)](swiftui/localizedstringkey/stringinterpolation/appendliteral(_:).md)