iOS UIScrollView和控制器返回手势冲突解决方法

class gesturesconflictscrollview: uiscrollview {
  override func gesturerecognizershouldbegin(_ gesturerecognizer: uigesturerecognizer) -> bool {
    back(by: gesturerecognizer)
  }

  private final func back(by gesturerecognizer: uigesturerecognizer) -> bool {
    
    guard gesturerecognizer == pangesturerecognizer else { return true }
    // point.x < 0 代表左滑即手指从屏幕右向左移动 反之一样
    let point: cgpoint = pangesturerecognizer.translation(in: self)
    let state: uigesturerecognizer.state = gesturerecognizer.state
    let locdistance: cgfloat = uiscreen.main.bounds.size.width
    
    if state == .began || state == .possible {
      let locationpoint = gesturerecognizer.location(in: self)
      if point.x > 0 && locationpoint.x < locdistance && contentoffset.x <= 0 {
        return false
      }
      let pagecount = contentsize.width / uiscreen.main.bounds.size.width
      let criticalpoint = pagecount < 2 ? locdistance : locdistance * (pagecount - 1)
      if point.x < 0 && contentoffset.x == criticalpoint {
        return false
      }
    }
    return true
  }
}