AppEnum

protocol · iOS 16.0+ · SDK 27.1

protocol AppEnum : AppValue, StaticDisplayRepresentable, RawRepresentable where Self.RawValue : LosslessStringConvertible

An interface to express that a custom type has a predefined, static set of values. When you want an app intent parameter or app entity property to have a fixed set of values, set the type of the underlying property to one that adopts the `AppEnum` protocol. In custom code, you use enumerations to limit the number of values available to a property of that type. For example, a fitness app might specify the available workout types using an enumeration instead of a string, because the enumeration requires someone to choose only known values. The `AppEnum` protocol adds metadata that Siri and other system features require to interact with your enumeration or custom type. Add the `AppEnum` protocol to an existing enumeration or type you plan to use in an app intent or app entity. For best results, base your enumeration on a type that’s easily convertible to a string such as the <doc://com.apple.documentation/documentation/swift/string> or <doc://com.apple.documentation/documentation/swift/int> type. The `AppEnum` protocol adds conformance to several other protocols to your type, including the ``TypeDisplayRepresentable`` and ``CaseDisplayRepresentable`` protocols. You’re responsible for implementing these protocols and providing descriptions of your type and each of the cases it contains. The following example shows an enumeration that a workout app uses to specify the available activities. The implementations of the ``TypeDisplayRepresentable/typeDisplayRepresentation`` and ``CaseDisplayRepresentable/caseDisplayRepresentations`` properties provide the protocol-mandated descriptions of the type and each activity. The system uses your descriptions in dialogs and to resolve parameters more quickly. ```swift enum ActivityStyle: String, AppEnum { case biking case equestrian case hiking case jogging case crossCountrySkiing case snowshoeing // Describe the overall type. static var typeDisplayRepresentation: TypeDisplayRepresentation { TypeDisplayRepresentation( name: LocalizedStringResource("Activity style", table: "AppIntents"), numericFormat: LocalizedStringResource("\(placeholder: .int) data", table: "AppIntents")) } // Describe the individual cases. static var caseDisplayRepresentations: [Self: DisplayRepresentation] = [ .biking: DisplayRepresentation(title: "Biking", subtitle: "Mountain bike ride"), .equestrian: DisplayRepresentation(title: "Equestrian", subtitle: "Equestrian sports"), .hiking: DisplayRepresentation(title: "Hiking", subtitle: "A lengthy outdoor walk"), .jogging: DisplayRepresentation(title: "Jogging", subtitle: "A gentle run"), .crossCountrySkiing: DisplayRepresentation(title: "Skiing", subtitle: "Cross-country skiing"), .snowshoeing: DisplayRepresentation(title: "Snowshoeing", subtitle: "Walking in the snow") ] } ``` > Note: Don’t adopt the ``AppEntity`` and `AppEnum` protocols in the same type. An app entity type represents data that can change dynamically, whereas an `AppEnum` represents static data that doesn’t change.

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