BottomSheetPresentationController_8.swift

@objc private func pannedPresentedView(_ recognizer: UIPanGestureRecognizer) {
    guard let presentedView = presentedView else {
        return
    }
    
    switch recognizer.state {
    case .began:
        transitioningDelegate?.transition.wantsInteractiveStart = true
    
    case .changed:
        let translation = recognizer.translation(in: presentedView)
        didGestureTranslationChange(translation)
    case .ended:
        let translation = recognizer.translation(in: presentedView)
        let progress = translation.y / presentedView.frame.height

        if progress > dismissThreshold {
            dismiss(withInteraction: true)
            transitioningDelegate?.transition.finish()
        } else {
            UIView.animate(withDuration: 0.2) {
                presentedView.transform = .identity
            }
            transitioningDelegate?.transition.cancel()
        }
    case .cancelled, .failed:
        break
    default:
        break
    }
}