以编程方式按钮自动布局？

Question

大家好，我想将我的按钮放在屏幕的下部，但我没有得到正确的代码。按钮太小，太大，在右上角或左下角，...但应该在下屏中间居中。

我用这些代码试过了：

nextButton.translatesAutoresizingMaskIntoConstraints = false
        
        nextButton.centerXAnchor.constraint(equalTo: view.centerXAnchor)
        nextButton.centerYAnchor.constraint(equalTo: view.centerYAnchor)
        nextButton.widthAnchor.constraint(equalTo: view.widthAnchor, constant: 97)
        nextButton.heightAnchor.constraint(equalTo: view.heightAnchor, constant: 50)

或

backButton.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20).isActive = true
       backButton.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20).isActive = true
       backButton.heightAnchor.constraint(equalToConstant: 50).isActive = true
       backButton.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

谁能告诉我该怎么做才能让它发挥作用？我认为使用 topAnchor 会很简单:(

Answer 1

这会将其定位在屏幕的底部中央

nextButton.translatesAutoresizingMaskIntoConstraints = false
    
NSLayoutConstraint.activate([
    nextButton.centerXAnchor.constraint(equalTo: view.centerXAnchor),
    nextButton.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant:-20),
    nextButton.widthAnchor.constraint(equalToConstant: 50),
    nextButton.heightAnchor.constraint(equalToConstant: 50) 
])

Answer 2

问题是您使用的是 centerYAnchor 而不是 bottomAnchor

替换

nextButton.centerYAnchor.constraint(equalTo: view.centerYAnchor)

和

let spacingConstant = 10.0
nextButton.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -spacingConstant)

以编程方式按钮自动布局？

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