---
title: PredicateExpressions.Variable
framework: foundation
role: symbol
role_heading: Structure
path: foundation/predicateexpressions/variable
---

# PredicateExpressions.Variable

## Declaration

```swift
struct Variable<Output>
```

## Topics

### Initializers

- [init()](foundation/predicateexpressions/variable/init().md)

### Instance Properties

- [key](foundation/predicateexpressions/variable/key.md)

## Relationships

### Conforms To

- [Copyable](swift/copyable.md)
- [CustomStringConvertible](swift/customstringconvertible.md)
- [Decodable](swift/decodable.md)
- [Encodable](swift/encodable.md)
- [Escapable](swift/escapable.md)
- [PredicateExpression](foundation/predicateexpression.md)
- [Sendable](swift/sendable.md)
- [SendableMetatype](swift/sendablemetatype.md)
- [StandardPredicateExpression](foundation/standardpredicateexpression.md)