# Animatable A type that describes how to animate a property of a view. ``` protocol Animatable ``` ## Overview When an animatable value changes inside a [`withAnimation(_:_:)`](/documentation/SwiftUI/withAnimation(_:_:)) block (or is affected by an `animation(_:value:)` modifier), SwiftUI reads the old and new [`animatableData`](/documentation/SwiftUI/Animatable/animatableData-6nydg) values, then interpolates between them over successive frames using [`VectorArithmetic`](/documentation/SwiftUI/VectorArithmetic) operations. The framework calls the [`animatableData`](/documentation/SwiftUI/Animatable/animatableData-6nydg) setter on each frame, giving your type a chance to update any derived state. ### Use the Animatable macro To conform a type to the `Animatable` protocol, use the [`Animatable()`](/documentation/SwiftUI/Animatable()) macro to avoid writing the [`animatableData`](/documentation/SwiftUI/Animatable/animatableData-6nydg) property by hand: ``` @Animatable struct RingSegment: Shape { var startAngle: Angle var endAngle: Angle // ... } ``` The macro inspects every stored property. Properties whose types conform to `VectorArithmetic` or `Animatable` are included in the synthesized [`animatableData`](/documentation/SwiftUI/Animatable/animatableData-6nydg). If a property cannot participate, the macro emits an error suggesting you mark it with [`AnimatableIgnored()`](/documentation/SwiftUI/AnimatableIgnored()) or conform its type to `VectorArithmetic` or `Animatable`: ``` @Animatable struct RingSegment: Shape { var startAngle: Angle var endAngle: Angle @AnimatableIgnored var isOpaque: Bool // ... } ``` ### Manual conformance for custom interpolation Reach for a handwritten [`animatableData`](/documentation/SwiftUI/Animatable/animatableData-6nydg) when the interpolated value needs custom logic that does not correspond one-to-one with a stored property, such as normalization, clamping, or driving a derived value. Use [`AnimatableValues`](/documentation/SwiftUI/AnimatableValues) (26.0+ releases) to group multiple animated properties, or [`AnimatablePair`](/documentation/SwiftUI/AnimatablePair) on earlier deployment targets: ``` struct WaveShape: Shape { var amplitude: CGFloat var phase: CGFloat var maxAmplitude: CGFloat var animatableData: AnimatableValues { get { AnimatableValues(amplitude, phase) } set { amplitude = min( max(newValue.value.0, 0), maxAmplitude) phase = newValue.value.1 .truncatingRemainder( dividingBy: 2 * .pi) } } // ... } ``` ## Topics ### Animating data [`Animatable()`](/documentation/SwiftUI/Animatable()) A member and extension macro that, when applied to a struct, class or enum declaration, synthesizes the conformance to `Animatable` and its requirement, the `animatableData` property using the existing animatable properties of the type this macro is applied to. [`AnimatableIgnored()`](/documentation/SwiftUI/AnimatableIgnored()) An accessor macro that marks a property of a type to be excluded from the `animatableData` synthesis: [`animatableData`](/documentation/SwiftUI/Animatable/animatableData-6nydg) The data to animate. [`AnimatableData`](/documentation/SwiftUI/Animatable/AnimatableData-swift.associatedtype) The type defining the data to animate. --- 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)