# Trait A package trait. ``` struct Trait ``` ## Overview A trait is a package feature that expresses conditional compilation and potentially optional dependencies. It is typically used to expose additional or extended API for the package. When you define a trait on a package, the package manager uses the name of that trait as a conditional block for the package’s code. Use the conditional block to enable imports or code paths for that trait. For example, a trait with the canonical name `MyTrait` allows you to use the name as a conditional block: ```swift #if MyTrait // additional imports or APIs that MyTrait enables #endif // MyTrait ``` > Important: Traits must be strictly additive. Enabling a trait **must not** remove API. If your conditional code requires a dependency that you want to enable only when the trait is enabled, add a conditional declaration to the target dependencies, then include the import statement within the conditional block. The following example illustrates enabling the dependency `MyDependency` when the trait `Trait1` is enabled: ```swift targets: [ .target( name: "MyTarget", dependencies: [ .product( name: "MyAPI", package: "MyDependency", condition: .when(traits: ["Trait1"]) ) ] ), ] ``` Coordinate a declaration like the example above with code that imports the dependency in a conditional block: ```swift #if Trait1 import MyAPI #endif // Trait1 ``` ## Topics ### Initializers [`init(name: String, description: String?, enabledTraits: Set)`](/documentation/PackageDescription/Trait/init(name:description:enabledTraits:)) Creates a trait with a name, a description, and set of additional traits it enables. [`init(stringLiteral: StringLiteralType)`](/documentation/PackageDescription/Trait/init(stringLiteral:)) Creates a trait with the name you provide. ### Instance Properties [`var description: String?`](/documentation/PackageDescription/Trait/description) The trait’s description. [`var enabledTraits: Set`](/documentation/PackageDescription/Trait/enabledTraits) A set of other traits of this package that this trait enables. [`var name: String`](/documentation/PackageDescription/Trait/name) The trait’s canonical name. ### Type Methods [`static func `default`(enabledTraits: Set) -> Trait`](/documentation/PackageDescription/Trait/default(enabledTraits:)) Declares the default traits for this package. [`static func trait(name: String, description: String?, enabledTraits: Set) -> Trait`](/documentation/PackageDescription/Trait/trait(name:description:enabledTraits:)) Creates a trait with a name, a description, and set of additional traits it enables. ## Relationships ### Conforms To [`ExpressibleByStringLiteral`](/documentation/Swift/ExpressibleByStringLiteral) [`SendableMetatype`](/documentation/Swift/SendableMetatype) [`Sendable`](/documentation/Swift/Sendable) [`ExpressibleByExtendedGraphemeClusterLiteral`](/documentation/Swift/ExpressibleByExtendedGraphemeClusterLiteral) [`ExpressibleByUnicodeScalarLiteral`](/documentation/Swift/ExpressibleByUnicodeScalarLiteral) [`Hashable`](/documentation/Swift/Hashable) [`Equatable`](/documentation/Swift/Equatable) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)