问题描述
我正在尝试在 UIStackView 中对齐和缩放图像:
class logoLine: UIViewController {
override func viewDidLoad() {
let label = UILabel()
label.text = "powered by"
label.textColor = .label
label.textAlignment = .center
let logoToUse = UIImage(named: "Image")
let imageView = UIImageView(image: logoToUse!)
let stackView = UIStackView(arrangedSubviews: [label,imageView])
stackView.axis = .vertical
stackView.distribution = .fillProportionally
view.addSubview(stackView)
stackView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
imageView.widthAnchor.constraint(equalToConstant: 50),// this gets ignored
stackView.topAnchor.constraint(equalTo: self.view.topAnchor),stackView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),stackView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor),view.heightAnchor.constraint(equalTo: stackView.heightAnchor)
])
}
}
问题:为什么 UIImageView 忽略了我的 50pt 的 widthAnchor 约束,为什么原始图像的纵横比会改变?如何将 UIImage(或 UIImageView)限制为例如屏幕宽度的一半并保持纵横比?
解决方法
默认情况下,垂直堆栈视图具有 .alignment = .fill
... 因此它将拉伸排列的子视图以“填充堆栈视图的宽度。”
改为:
stackView.alignment = .center
顺便说一下,去掉 stackView.distribution = .fillProportionally
...几乎肯定不是你想要的。