@Random

A property wrapper that assigns a stable random value to a member variable, persisting across multiple body invocations.

Use this to introduce variation in animations without relying on @State.

For example

struct RandomOffsetTransition: Transition {
    @Random(distance: 20) var offset: CGSize

    func body(content: Content, phase: TransitionPhase) -> some View {
        content.offset(phase.isIdentity ? .zero : offset)
    }
}

will create a transition that animates the view from a random offset.

Fixed Seeds

By default, different instances of the same View or ViewModifier generate unique @Random values. To ensure consistency, you can provide a custom seed via the property wrapper’s projectedValue's seed value.

For example, assigning a model’s hashValue to $greeting.seed ensures stability when the view gets recreated, say in a LazyVStack.

struct Cell: View {
    @Random(in: "Hello", "Bonjour", "Willkommen") var greeting

    var model: Model

    init(model: Model) {
        self.model = model
        $greeting.seed = model.hashValue
    }

    var body: some View {
      // The same `model` will get the same `greeting`, every time.
      Text("\(greeting), \(model.name)!")
    }
}

This way, each Cell instance with the same model will always produce the same greeting.

Important

Some Swift types, like String, generate different hashValues across app launches. For values that persist across launches, use a stable identifier, such as a user ID.