UIScrollView作为辅助视图的问题

UIScrollView 作为辅助视图。我有一个名为 newDogView 并在代码中设置其约束。

newDogView

以下是相关代码:

override func viewWillLayoutSubviews() {
    newDogView.translatesAutoresizingMaskIntoConstraints = false
    newDogScrollView.translatesAutoresizingMaskIntoConstraints = false
    newDogScrollView.heightAnchor.constraint(equalToConstant: 320.0).isActive = true
    newDogScrollView.widthAnchor.constraint(equalToConstant: 960.0).isActive = true
    newDogScrollView.contentSize = CGSize(width: 320, height: 320)
    newDogView.heightAnchor.constraint(equalToConstant: 320.0).isActive = true
    newDogView.widthAnchor.constraint(equalToConstant: 320.0).isActive = true
    newDogView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
    newDogView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
}

我不确定是否应该设置newDogView的高度和宽度。

以下是我当前的视图层次结构和警告:

这是我当前的故事板:

Content View 和 Scroll View .