视图高度换行子视图内容

Question

我想在超级视图左侧添加图像和超级视图的自定义标签中心。超级视图的高度也必须包裹孩子。我还将超级视图添加到堆栈中（填充、填充分布和对齐）。代码如下，但 imageview 未显示。这里有什么问题？

let topView = UIView()
topView.translatesAutoresizingMaskIntoConstraints = false
topView.heightAnchor.constraint(equalToConstant: 30).isActive = true
topView.widthAnchor.constraint(equalToConstant: self.view.frame.size.width).isActive = true

let backImageView: UIImageView = UIImageView()
backImageView.isUserInteractionEnabled = true
backImageView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(backButtonClicked)))
backImageView.image = UIImage(named: "backButton")
backImageView.contentMode = .scaleAspectFit
backImageView.clipsToBounds = true

topView.addSubview(backImageView)
backImageView.leftAnchor.constraint(equalTo: topView.leftAnchor).isActive = true
backImageView.topAnchor.constraint(equalTo: topView.topAnchor).isActive = true
backImageView.bottomAnchor.constraint(equalTo: topView.bottomAnchor).isActive = true
backImageView.centerYAnchor.constraint(equalTo: topView.centerYAnchor).isActive = true

topView.addSubview(titleText)
titleText.centerXAnchor.constraint(equalTo: topView.centerXAnchor).isActive = true
titleText.centerYAnchor.constraint(equalTo: topView.centerYAnchor).isActive = true

Answer 1

我认为你的问题在于backImageView Y 约束

backImageView.centerYAnchor.constraint(equalTo: topView.centerYAnchor).isActive = true

应该是

backImageView.centerXAnchor.constraint(equalTo: topView.centerXAnchor).isActive = true

Y 代表 vertical 轴，因此在您的 4 个约束中，您有 3 个垂直约束和 1 个水平约束。将其替换为centerXAnchor，您应该会很好。