linear(duration:)

Declaration

static func linear(duration: TimeInterval) -> Animation

Parameters

• duration:

  The length of time, expressed in seconds, that the animation takes to complete.

Return Value

A linear animation with a specified duration.

Discussion

A linear animation provides a mechanical feel to the motion because its speed is consistent from start to finish of the animation. This constant speed makes a linear animation ideal for animating the movement of objects where changes in the speed might feel awkward, such as with an activity indicator.

Use linear(duration:) when you want to specify the time it takes for the animation to complete. Otherwise, use linear to perform the animation for a default length of time.

The following code shows an example of using linear animation with a duration of two seconds to animate the movement of a circle as it moves between the leading and trailing edges of the view. The color of the circle also animates from red to blue as it moves across the view.

struct ContentView: View {
    @State private var isActive = false

    var body: some View {
        VStack(alignment: isActive ? .trailing : .leading) {
            Circle()
                .fill(isActive ? Color.red : Color.blue)
                .frame(width: 50, height: 50)

            Button("Animate") {
                withAnimation(.linear(duration: 2.0)) {
                    isActive.toggle()
                }
            }
            .frame(maxWidth: .infinity)
        }
    }
}

See Also

Getting linear animations

• linear