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PropertyWrapper that can be applied to `Equatable` properties of `ObservableObject` to notify observers of unique changes.
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| /// PropertyWrapper that can be applied to `Equatable` properties of `ObservableObject` to notify observers of unique changes | |
| @propertyWrapper | |
| struct UniqueChanges<Element: Equatable> { | |
| init(wrappedValue: Element) { | |
| self._wrappedValue = wrappedValue | |
| } | |
| @available(*, unavailable, message: "@UniqueChanges can only be applied to types that conform to `ObservableObject`") | |
| var wrappedValue: Element { | |
| get { fatalError() } | |
| set { fatalError() } | |
| } | |
| private var _wrappedValue: Element | |
| // Classes get and set `wrappedValue` using this subscript. | |
| static subscript<T: ObservableObject>(_enclosingInstance instance: T, | |
| wrapped wrappedKeyPath: ReferenceWritableKeyPath<T, Element>, | |
| storage storageKeyPath: ReferenceWritableKeyPath<T, UniqueChanges>) -> Element where T.ObjectWillChangePublisher == ObservableObjectPublisher { | |
| get { | |
| instance[keyPath: storageKeyPath]._wrappedValue | |
| } | |
| set { | |
| guard instance[keyPath: storageKeyPath]._wrappedValue != newValue else { return } | |
| instance.objectWillChange.send() | |
| instance[keyPath: storageKeyPath]._wrappedValue = newValue | |
| } | |
| } | |
| } |
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