The smoothDamp function in Unity implemented using Swift

smoothDamp.swift

/**
 * Gradually changes a value towards a desired goal over time - implemented from Unity C#
 */
public func smoothDamp(current c: CGFloat, target t: CGFloat, currentVelocity: inout CGFloat, smoothTime time: CGFloat, maxSpeed: CGFloat = CGFloat.infinity, deltaTime: CGFloat) -> CGFloat {
    let smoothTime = max(0.0001, time)
    let num  = 2 / smoothTime
    let num2 = num * deltaTime
    let num3 = 1 / (1 + num2 + 0.48 * num2 * num2 + 0.235 * num2 * num2 * num2)
    var num4 = c - t
    let num5 = t
    let num6 = maxSpeed * smoothTime
    num4 = min(max(num4, -num6), num6)
    let target = c - num4
    let num7 = (currentVelocity + num * num4) * deltaTime
    currentVelocity = (currentVelocity - num * num7) * num3
    var num8 = target + (num4 + num7) * num3
    if (num5 - c > 0) == (num8 > num5) {
        num8 = num5
        currentVelocity = (num8 - num5) / deltaTime
    }
    return num8
}