Animation about pulley HOT 4 OPEN

final class BankBuilder {
        static func build() -> BankViewController {
		let mainContentVC = UIStoryboard.bank.instantiateViewController(AccountViewController.self)
		let drawerContentVC = UIStoryboard.bank.instantiateViewController(OperationsViewController.self)
		let viewController = BankViewController(contentViewController: mainContentVC, drawerViewController: drawerContentVC)
...
                 return viewController
        }
}

final class BankViewController: PulleyViewController {
	var tabBar: TabBarController? {
		tabBarController as? TabBarController
	}
...
	override func drawerPositionDidChange(drawer: PulleyViewController, bottomSafeArea: CGFloat) {
		guard pulleyPosition != drawer.drawerPosition else { return }
		pulleyPosition = drawer.drawerPosition

		switch drawer.drawerPosition {
		case .collapsed:
			interactor?.request(.didCollapseTable)
			tabBar?.didScrollUp()
		case .partiallyRevealed:
			interactor?.request(.didExpandTable)
			tabBar?.didScrollDown()
		default: return
		}
	}
}

final class TabBarController: UITabBarController {
...
	func didScrollDown() {
		lowerTabBar()
	}
...
	private func lowerTabBar() {
		guard customTabBar.frame.origin.y == tabBarOriginMinY else { return }
		var frame = customTabBar.frame
		frame.origin.y = tabBarOriginMaxY
		animate {
			self.customTabBar.frame = frame
		}
	}
...
	private func animate(block: @escaping () -> Void) {
		UIView.animate(
			withDuration: Appearance.animationDuration,
			delay: Appearance.animationDelay,
			usingSpringWithDamping: Appearance.springWithDamping,
			initialSpringVelocity: Appearance.initialSpringVelocity,
			options: Appearance.animationOptions,
			animations: {
				block()
		})
	}
...
}

private struct Appearance {
	static let animationDuration: TimeInterval = 1
	static let animationDelay: TimeInterval = 0
	static let springWithDamping: CGFloat = 0.7
	static let initialSpringVelocity: CGFloat = 1
	static let animationOptions: UIView.AnimationOptions = [.curveEaseInOut]
}