NSScrollView截断文本，没有滚动条

Question

我很难为文本文件显示设置NSScrollView。

定义了一个适当大小的窗口：

......
    let contentRect = NSMakeRect(0.0, 0.0, 800, 600)
    let styleMask:NSWindow.StyleMask = [.titled, .closable, .miniaturizable, .resizable]
    let window = NSWindow(contentRect:contentRect, styleMask:styleMask, backing:.buffered, defer:true)
    window.minSize = NSMakeSize(800.0, 600.0)
    window.isReleasedWhenClosed = false
    window.tabbingMode = .disallowed
    window.makeKeyAndOrderFront(nil)
    window.center() // Wait until after makeKeyAndOrderFront so the window sizes properly first
    window.title = NSLocalizedString("GCode File", comment:"GCode File window")
......

设置滚动视图并将其放入窗口，然后设置窗口约束：

......
    let scrollView = NSScrollView(frame: (window.contentView?.frame)!)
    scrollView.translatesAutoresizingMaskIntoConstraints = false
    scrollView.borderType = .noBorder
    scrollView.backgroundColor = NSColor.gray
    scrollView.hasVerticalScroller = true

    window.contentView?.addSubview(scrollView)
    window.contentView?.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[scrollView]|", options: [], metrics: nil, views: ["scrollView": scrollView]))
    window.contentView?.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[scrollView]|", options: [], metrics: nil, views: ["scrollView": scrollView]))

......

设置clipview并将clipview设置为scrollview的内容视图，然后配置scrollview和clipview的约束：

......
    let clipView = NSClipView()
    clipView.translatesAutoresizingMaskIntoConstraints = false
    scrollView.contentView = clipView
    scrollView.addConstraint(NSLayoutConstraint(item: clipView, attribute: .left, relatedBy: .equal, toItem: scrollView, attribute: .left, multiplier: 1.0, constant: 0))
    scrollView.addConstraint(NSLayoutConstraint(item: clipView, attribute: .top, relatedBy: .equal, toItem: scrollView, attribute: .top, multiplier: 1.0, constant: 0))
    scrollView.addConstraint(NSLayoutConstraint(item: clipView, attribute: .right, relatedBy: .equal, toItem: scrollView, attribute: .right, multiplier: 1.0, constant: 0))
    scrollView.addConstraint(NSLayoutConstraint(item: clipView, attribute: .bottom, relatedBy: .equal, toItem: scrollView, attribute: .bottom, multiplier: 1.0, constant: 0))
......

设置nstextview并将文件内容加载到nstextview：

......
    var textView: NSTextView!
    var textStorage: NSTextStorage!
    textStorage = NSTextStorage()
    let layoutManager = NSLayoutManager()
    textStorage.addLayoutManager(layoutManager)
    let textContainer = NSTextContainer(containerSize: window.contentView!.bounds.size)
    layoutManager.addTextContainer(textContainer)
    textView = NSTextView(frame: window.contentView!.bounds, textContainer: textContainer)
    textView.isEditable = true
    textView.isSelectable = true
    textView.textStorage?.append(file)
    scrollView.documentView = textView
......

然后我运行该应用程序，将窗口和内容呈现为：

怎么了？我看不到从文件加载的全文（被截断），也没有垂直滚动条显示。我相信约束配置中缺少一些东西。

如果有经验，请提出建议！