---
title: StringInterpolation
framework: swift
role: symbol
role_heading: Associated Type
path: swift/expressiblebystringinterpolation/stringinterpolation
---

# StringInterpolation

The type each segment of a string literal containing interpolations should be appended to.

## Declaration

```swift
associatedtype StringInterpolation : StringInterpolationProtocol = DefaultStringInterpolation where Self.StringLiteralType == Self.StringInterpolation.StringLiteralType
```

## Discussion

Discussion The StringLiteralType of an interpolation type must match the StringLiteralType of the conforming type.