ios - UIButton 高度和自动布局

Question

在我的一个 ViewController 中，我使用底部有两个按钮的 UIView。显然，我想适应屏幕的两个按钮，所以我使用这个:

leftButton.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: -16).isActive = true
rightButton.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: -16).isActive = true
//16 points between the buttons
leftButton.rightAnchor.constraint(equalTo: rightButton.leftAnchor, constant: -16).isActive = true 
//right alignment for the buttons
rightButton.rightAnchor.constraint(equalTo: self.rightAnchor, constant: -16).isActive = true 
//left padding for the left button - 16 points
leftButton.leftAnchor.constraint(greaterThanOrEqualTo: self.leftAnchor, constant: 16).isActive = true 

//rightButton can't be less wide than 1/3 of its superview
rightButton.widthAnchor.constraint(greaterThanOrEqualToConstant: widthOfTheView / 3).isActive = true

它可以工作，但是如果我的左按钮标题很长怎么办？我的左键的高度变大了，没关系。但是我的右键还是不是很高，看起来略显丑陋。

好的，但是如果我告诉自动布局我希望右侧按钮的高度与左侧按钮的高度相同怎么办。

rightButton.heightAnchor.constraint(equalTo: leftButton.heightAnchor, constant: 0).isActive = true

我认为这是一个解决方案，但我却得到了这个:

从技术上讲，他们的高度是相等的，但这不是我想要的结果。

我认为，也许问题出在按钮内的 UIEdgeInsets 中，但事实并非如此(我取消了这一行，结果是一样的)。

我想我不能选择两个按钮之间的最大高度并将其用作约束的常量，因为在这个阶段它们各自的框架为零。

我尝试使用另一个 UIView 作为这两个按钮的容器，但结果是一样的。

当然，我可以通过关闭自动布局并计算按钮大小和框架来解决这个问题，但我现在不想这样做。

那么，我做错了什么？

Answer 1

这可以很容易地通过 UIStackView 设置

.axis = .horizontal
.alignment = .fill
.distribution = .fillEqually
.spacing = 12

自动调整尺寸变化:

代码如下:

class MultilineRoundedButton: UIButton {

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        commonInit()
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        commonInit()
    }

    func commonInit() -> Void {
        self.titleLabel?.numberOfLines = 0
        self.titleLabel?.textAlignment = .center
        self.setContentHuggingPriority(UILayoutPriority.defaultLow + 1, for: .vertical)
        self.setContentHuggingPriority(UILayoutPriority.defaultLow + 1, for: .horizontal)
        self.layer.cornerRadius = 8
    }

    override var intrinsicContentSize: CGSize {
        let size = self.titleLabel!.intrinsicContentSize
        return CGSize(width: size.width + contentEdgeInsets.left + contentEdgeInsets.right, height: size.height + contentEdgeInsets.top + contentEdgeInsets.bottom)
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        titleLabel?.preferredMaxLayoutWidth = self.titleLabel!.frame.size.width
    }
}

class TwoButtonsView: UIView {

    let theStackView: UIStackView = {
        let v = UIStackView()
        v.translatesAutoresizingMaskIntoConstraints = false
        v.axis = .horizontal
        v.alignment = .fill
        v.distribution = .fillEqually
        v.spacing = 16
        return v
    }()

    let leftButton: MultilineRoundedButton = {
        let v = MultilineRoundedButton()
        v.translatesAutoresizingMaskIntoConstraints = false
        v.setTitle("Really (really!) long first button title", for: .normal)
        v.backgroundColor = UIColor(red: 184.0 / 255.0, green: 233.0 / 255.0, blue: 133.0 / 255.0, alpha: 1.0)
        return v
    }()

    let rightButton: MultilineRoundedButton = {
        let v = MultilineRoundedButton()
        v.translatesAutoresizingMaskIntoConstraints = false
        v.setTitle("Second title", for: .normal)
        v.backgroundColor = UIColor(red:  74.0 / 255.0, green: 143.0 / 255.0, blue: 226.0 / 255.0, alpha: 1.0)
        return v
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)
        commonInit()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        commonInit()
    }

    func commonInit() -> Void {

        leftButton.titleLabel?.font = UIFont.systemFont(ofSize: 24.0, weight: .bold)
        rightButton.titleLabel?.font = leftButton.titleLabel?.font

        addSubview(theStackView)
        theStackView.addArrangedSubview(leftButton)
        theStackView.addArrangedSubview(rightButton)

        NSLayoutConstraint.activate([
            theStackView.topAnchor.constraint(equalTo: topAnchor),
            theStackView.bottomAnchor.constraint(equalTo: bottomAnchor),
            theStackView.leadingAnchor.constraint(equalTo: leadingAnchor),
            theStackView.trailingAnchor.constraint(equalTo: trailingAnchor),
            ])

    }

}

class TwoButtonViewController: UIViewController {

    let buttonsView: TwoButtonsView = {
        let v = TwoButtonsView()
        v.translatesAutoresizingMaskIntoConstraints = false
        return v
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        view.addSubview(buttonsView)

        NSLayoutConstraint.activate([
            buttonsView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor, constant: -20.0),
            buttonsView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor, constant: 20.0),
            buttonsView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor, constant: -20.0),
            ])
    }

}