AdditionalSafeAreaInsets_3.swift

let duration = userInfo[UIResponder.keyboardAnimationDurationUserInfoKey]
    .flatMap { $0 as? Double } ?? 0.25
if duration > 0 {
    let curve = userInfo[UIResponder.keyboardAnimationCurveUserInfoKey]
    .flatMap { $0 as? Int }
    .flatMap { UIView.AnimationCurve(rawValue: $0) } ?? .easeInOut
    UIViewPropertyAnimator(duration: duration, curve: curve) {
        viewController.view.layoutIfNeeded()
    }
    .startAnimation()
} else {
    viewController.view.layoutIfNeeded()
}