swiftui-animation-ref

Conform your view to the Animatable protocol and define animatableData using VectorArithmetic. This tells SwiftUI how to interpolate your custom property during animations, enabling smooth transitions for types like Int, CGPoint, or custom structs.

Model values are your source of truth and don't change during animation; presentation values reflect the interpolated state displayed on screen. Understanding this distinction is critical for debugging animations and ensuring your logic responds to the correct value.

Spring animations create natural, physics-based motion with bounce and decay; timing curves provide precise, predictable easing. Use spring for interactive UI feedback and timing curves for controlled, linear transitions or specific pacing requirements.

VectorArithmetic is a protocol that defines how SwiftUI interpolates between values during animation. It requires conforming types to support addition, subtraction, and scalar multiplication, enabling smooth transitions for any custom data structure.

The @Animatable macro is available in iOS 26 and later, providing a simplified way to make properties animatable without manually implementing the Animatable protocol. For earlier iOS versions, implement Animatable and animatableData directly.

SwiftUI only animates types that conform to VectorArithmetic. Int and String don't conform by default. Wrap them in an Animatable-conforming type or use animatableData to map them to an animatable representation like Double or CGFloat.