UIKit-UINavigationController

question

case：我想在一个stackView里面放到三个不同颜色的view(约束设置了wight:120,height:20),然后分别间隔10.然后通过navigationController来显示。我希望整个VC的大小根据stackView来变。
问题：发现通过preferredContentSize和view.systemLayoutSizeFitting总会多一点高度，从而导致因为stackView固定了间距10.直接强行将最后一个view的高度拉高了

override var preferredContentSize: CGSize {
        set {
            super.preferredContentSize = newValue
        }
        get {
            return stackView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
    }

stackView.distribution = .equalSpacing

stackView.distribution = .fill

最终应该改为

override var preferredContentSize: CGSize {
        set {
            super.preferredContentSize = newValue
        }
        get {
            let navBarHeight = navigationController?.navigationBar.bounds.height ?? 0
            print("preferredContentSize height:\(stackView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize).height),width:\(stackView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize).width)，navBarHeight：\(navBarHeight)")
            let fitSize = stackView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
            return CGSize(width: fitSize.width, height: fitSize.height - navBarHeight)
        }
    }

key:给UINavigationController的preferredContentSize需要减去navBarHeight，因为systemLayoutSizeFit获取的会包含navigationBarHeight,就需要减去这部分