UIButton 宽度的自动布局问题

Question

    signUpButton.translatesAutoresizingMaskIntoConstraints = false
    signUpButton.widthAnchor.constraint(equalToConstant: 128).isActive = true
    signUpButton.heightAnchor.constraint(equalToConstant: 64).isActive = true
    signUpButton.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
    signUpButton.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
    signUpButton.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor)

• NSLayoutConstraint: UIButton:'Sign Up'.width == 128（活动），
• NSLayoutConstraint：H:|-(0)-[UIButton:'Sign Up']（活动，名称：'|':UIView:），
• NSLayoutConstraint: UIButton:'Sign Up'.trailing == UIView:.trailing (active),
• NSLayoutConstraint: 'UIView-Encapsulated-Layout-Width' UIView:.width == 375（活动）

将尝试通过打破约束来恢复 NSLayoutConstraint: UIButton:'Sign Up'.width == 128 (active)>

我想将按钮放在具有一定宽度的前导和尾随锚点的中心，但是当我运行代码时，按钮会扩展到这些锚点。如何防止这种扩展？

Answer 1

由于您似乎希望在view 内水平居中按钮，您需要替换：

signUpButton.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
signUpButton.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true

与：

signUpButton.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true