Property wrapper implementation requirements (PropertyWrappers)

Overview

If a type is marked with the @propertyWrapper attribute, it must meet certain requirements to be a valid property wrapper.

First, all property wrapper types must have a property named wrappedValue. This property cannot be static and must have the same access level as the property wrapper type. If the property wrapper provides a projectedValue property, it is subject to the same requirements.

Second, none of a property wrapper’s initializers may be failable. Additionally, if a property wrapper initializer has a wrappedValue parameter, the type of that parameter must either be the same as the type of the wrappedValue property or an @autoclosure of that type.

See Also

• @dynamicCallable implementation requirements (DynamicCallable)
• Add @preconcurrency import (AddPreconcurrencyImport)
• Always enabled availability domains (AlwaysAvailableDomain)
• Argument matching for trailing closures (TrailingClosureMatching)
• Calling a mutating async actor-isolated method (ActorIsolatedMutatingAsync)
• Calling an actor-isolated method from a synchronous nonisolated context (ActorIsolatedCall)
• Captures in a `@Sendable` closure (SendableClosureCaptures)
• Compilation caching (CompilationCaching)
• Conforming to `StringInterpolationProtocol` (StringInterpolationConformance)
• Conversion from `@isolated(any)` function type to synchronous function type (ConversionFromIsolatedAnyToSynchronous)
• Cross-isolation data race (RegionIsolationCrossIsolationDataRace)
• Deprecated declaration warnings (DeprecatedDeclaration)
• Deprecated implementation-only imports (ImplementationOnlyDeprecated)
• Dynamic exclusivity (DynamicExclusivity)
• Embedded Swift language restrictions (EmbeddedRestrictions)