---
title: Parameter
framework: tipkit
role: symbol
role_heading: Structure
path: tipkit/tips/parameter
---

# Parameter

A type that monitors the state of its wrapped value to reevaluate any dependent tip rules when the value changes.

## Declaration

```swift
struct Parameter<Value> where Value : Decodable, Value : Encodable, Value : Sendable
```

## Overview

Overview You create a parameter by wrapping a conforming type with the @Parameter macro. An id is generated based on the parameter’s enclosing instance and the name of the property it is wrapping. note: Parameters are persistent by default. Wrapping a property with @Parameter will persist its value between app launches within the tips datastore. Passing ParameterOption.transient as an option will allow the parameter to reset to a default value the first time it is referenced. Tips must be configured using configure(_:) before a parameter’s value will be updated. Pair parameters with the tip properties you want to monitor. For example, to track whether someone has previously used a feature in your app, define a property wrapper, along with the parameter with the value you want to track in your tip as follows: struct LandmarksUser {     // Define the user interaction you want to use for a display rule.     @Parameter     static var hasFavoritedLandmark: Bool = false } Then construct a rule for your tip based on that parameter: struct FavoriteLandmarkTip: Tip {     var rules: [Rule] {         // Tip will only display when `hasFavoritedLandmark` is false.         #Rule(LandmarksUser.hasFavoritedLandmark) {             $0 == false         }     } }

## Topics

### Parameter options

- [ParameterOption.transient](tipkit/tips/parameteroption/transient.md)

## Relationships

### Conforms To

- [Copyable](swift/copyable.md)
- [Escapable](swift/escapable.md)
- [Identifiable](swift/identifiable.md)
- [Sendable](swift/sendable.md)
- [SendableMetatype](swift/sendablemetatype.md)

## See Also

### Related Documentation

- [Rule](tipkit/tips/rule.md)