Optional

public final class Optional<V> : AttributeKeyPathStringConvertible, AttributeProtocol where V : NSCoding, V : NSCopying

The containing type for optional transformable properties. Any type that conforms to NSCoding & NSCopying are supported.

class Animal: CoreStoreObject {
    let species = Value.Required<String>("species", initial: "")
    let nickname = Value.Optional<String>("nickname")
    let color = Transformable.Optional<UIColor>("color")
}

Important

Transformable.Optional properties are required to be stored properties. Computed properties will be ignored, including lazy and weak properties.

  • Initializes the metadata for the property.

    class Animal: CoreStoreObject {
    let species = Value.Required<String>("species", initial: "")
    let color = Transformable.Optional<UIColor>(
        "color",
        isTransient: true,
        customGetter: Animal.getColor(_:)
    )
}

private static func getColor(_ partialObject: PartialObject<Animal>) -> UIColor? {
    if let cachedColor = partialObject.primitiveValue(for: { $0.color }) {
        return cachedColor
    }
    let color: UIColor?
    switch partialObject.value(for: { $0.species }) {

    case "Swift": color = UIColor.orange
    case "Bulbasaur": color = UIColor.green
    default: return nil
    }
    partialObject.setPrimitiveValue(color, for: { $0.color })
    return color
}

    Declaration

    Swift

    public init(
    _ keyPath: KeyPathString,
    initial: @autoclosure @escaping () -> V? = nil,
    isTransient: Bool = false,
    allowsExternalBinaryDataStorage: Bool = false,
    versionHashModifier: @autoclosure @escaping () -> String? = nil,
    renamingIdentifier: @autoclosure @escaping () -> String? = nil,
    customGetter: ((_ partialObject: PartialObject<O>) -> V?)? = nil,
    customSetter: ((_ partialObject: PartialObject<O>, _ newValue: V?) -> Void)? = nil,
    affectedByKeyPaths: @autoclosure @escaping () -> Set<String> = [])

    Parameters

    keyPath

    the permanent attribute name for this property.
    initial

    the initial value for the property that is shared for all instances of this object. Note that this is evaluated during DataStack setup, not during object creation. Defaults to the ImportableAttributeType‘s empty value if not specified.
    isTransient

    true if the property is transient, otherwise false. Defaults to false if not specified. The transient flag specifies whether or not a property’s value is ignored when an object is saved to a persistent store. Transient properties are not saved to the persistent store, but are still managed for undo, redo, validation, and so on.
    allowsExternalBinaryDataStorage

    true if the attribute allows external binary storage, otherwise false.
    versionHashModifier

    used to mark or denote a property as being a different “version” than another even if all of the values which affect persistence are equal. (Such a difference is important in cases where the properties are unchanged but the format or content of its data are changed.)
    renamingIdentifier

    used to resolve naming conflicts between models. When creating an entity mapping between entities in two managed object models, a source entity property and a destination entity property that share the same identifier indicate that a property mapping should be configured to migrate from the source to the destination. If unset, the identifier will be the property’s name.
    customGetter

    use this closure as an “override” for the default property getter. The closure receives a PartialObject<O>, which acts as a fast, type-safe KVC interface for CoreStoreObject. The reason a CoreStoreObject instance is not passed directly is because the Core Data runtime is not aware of CoreStoreObject properties’ static typing, and so loading those info everytime KVO invokes this accessor method incurs a cumulative performance hit (especially in KVO-heavy operations such as ListMonitor observing.) When accessing the property value from PartialObject<O>, make sure to use PartialObject<O>.primitiveValue(for:) instead of PartialObject<O>.value(for:), which would unintentionally execute the same closure again recursively.
    customSetter

    use this closure as an “override” for the default property setter. The closure receives a PartialObject<O>, which acts as a fast, type-safe KVC interface for CoreStoreObject. The reason a CoreStoreObject instance is not passed directly is because the Core Data runtime is not aware of CoreStoreObject properties’ static typing, and so loading those info everytime KVO invokes this accessor method incurs a cumulative performance hit (especially in KVO-heavy operations such as ListMonitor observing.) When accessing the property value from PartialObject<O>, make sure to use PartialObject<O>.setPrimitiveValue(_:for:) instead of PartialObject<O>.setValue(_:for:), which would unintentionally execute the same closure again recursively.
    affectedByKeyPaths

    a set of key paths for properties whose values affect the value of the receiver. This is similar to NSManagedObject.keyPathsForValuesAffectingValue(forKey:).

  • The attribute value

    Declaration

    Swift

    public var value: ReturnValueType { get set }

AnyKeyPathStringConvertible

  • Declaration

    Swift

    public var cs_keyPathString: String { get }

KeyPathStringConvertible

AttributeKeyPathStringConvertible

TransformableContainer.Optional

Operations

  • Assigns an optional transformable value to the property. The operation

    animal.color .= UIColor.red

    is equivalent to

    animal.color.value = UIColor.red

    Declaration

    Swift

    public static func .= (property: TransformableContainer<O>.Optional<V>, newValue: V?)

  • Assigns an optional transformable value from another property. The operation

    animal.color .= anotherAnimal.color

    is equivalent to

    animal.color.value = anotherAnimal.color.value

    Declaration

    Swift

    public static func .= <O2>(property: TransformableContainer<O>.Optional<V>, property2: TransformableContainer<O2>.Optional<V>) where O2 : CoreStoreObject

  • Assigns a transformable value from another property. The operation

    animal.color .= anotherAnimal.color

    is equivalent to

    animal.color.value = anotherAnimal.color.value

    Declaration

    Swift

    public static func .= <O2>(property: TransformableContainer<O>.Optional<V>, property2: TransformableContainer<O2>.Required<V>) where O2 : CoreStoreObject