无法检测前进和后退的方向

Question

我有一个pageMenuController，当我左右滑动时，我需要检测其移动方向。我的委托方法是：

func pageMenuController(_ pageMenuController: PageMenuController, didScrollToPageAtIndex index: Int, direction: PageMenuNavigationDirection) {
        print(index)
        // The page view controller will begin scrolling to a new page.
    }
func pageMenuController(_ pageMenuController: PageMenuController, willScrollToPageAtIndex index: Int, direction: PageMenuNavigationDirection) {
}
func pageMenuController(_ pageMenuController: PageMenuController, scrollingProgress progress: CGFloat, direction: PageMenuNavigationDirection) {

    }
func pageMenuController(_ pageMenuController: PageMenuController, didSelectMenuItem index: Int, direction: PageMenuNavigationDirection) {
}

我正在添加我的代码以检测willScrollToPageAtIndex中的直接位置。如下所示：

func pageMenuController(_ pageMenuController: PageMenuController, willScrollToPageAtIndex index: Int, direction: PageMenuNavigationDirection) {
 print(index)
        print(PageMenuNavigationDirection.forward)
         print(PageMenuNavigationDirection.self)
        print(direction.hashValue)
        print(direction.rawValue)
         print(direction)
}

没有任何值像正向或反向打印。我的PageMenuNavigationDirection类是这样的：

import Foundation

@objc public enum PageMenuNavigationDirection: Int {

    /// Forward direction. Can be right in a horizontal orientation or down in a vertical orientation.
    case forward

    /// Reverse direction. Can be left in a horizontal orientation or up in a vertical orientation.
    case reverse
}

extension EMPageViewControllerNavigationDirection {

    var toPageMenuNavigationDirection: PageMenuNavigationDirection {
        switch self {
        case .forward:
            return .forward
        default:
            return .reverse
        }
    }
}

任何想法，当我左右滑动时如何获得指示？