indexPathForRow不会返回正确的值

我正在尝试使用3D Touch，除了下面的功能，一切都很好，当滚动时我无法获得正确的值indexPath和indexPathForRow(at: location)。此功能不能说用户是否滚动表格，并且始终将用户在应用中可以看到的第一行设置为第一行。indexPathForRow不会返回正确的值

我的代码：

func previewingContext(_ previewingContext: UIViewControllerPreviewing, viewControllerForLocation location: CGPoint) -> UIViewController? { 

     guard let indexPath = workoutTable?.indexPathForRow(at: location) else {return nil } 
     guard let cell = workoutTable?.cellForRow(at: indexPath) else {return nil } 
     guard let workoutDetailPeek = storyboard?.instantiateViewController(withIdentifier: "WorkoutDetailPeek") as? WorkoutDetailPeek else {print("else31"); return nil } 

     workoutDetailPeek.workoutId = "\(Int(workout[(indexPath as NSIndexPath).row].workoutId)!-2)" 
     workoutDetailPeek.preferredContentSize = CGSize(width: 400.0, height: 267.0) 
     previewingContext.sourceRect = cell.frame 
     return workoutDetailPeek 
}

我一直通过不同的3D触控实现，但这个功能似乎每个人都工作正常，除了我。

来源

2016-12-26 ali farhangmehr