布局约束不起作用 iOS swift

Question

我添加了前导 |拖尾 |顶部 |高度限制但视图不可见。

  let view = UIView()
  view.backgroundColor = .orange
  self.addSubview(view)
    
  NSLayoutConstraint.activate([
        view.leadingAnchor.constraint(equalTo: self.leadingAnchor),
        view.trailingAnchor.constraint(equalTo: self.trailingAnchor),
        view.topAnchor.constraint(equalTo: self.topAnchor, constant: 100),
        view.heightAnchor.constraint(equalToConstant: 300)
  ])

Answer 1

将视图添加为子视图时，您的代码应禁用 translatesAutoresizingMaskIntoConstraints。这意味着系统不会创建一组约束来复制视图的自动调整掩码指定的行为。

假设您的约束是正确的，您应该会在将属性设置为 false 后看到您的视图。

let view = UIView()
view.backgroundColor = .orange
view.translatesAutoresizingMaskIntoConstraints = false
self.addSubview(view)
    
NSLayoutConstraint.activate([
    view.leadingAnchor.constraint(equalTo: self.leadingAnchor),
    view.trailingAnchor.constraint(equalTo: self.trailingAnchor),
    view.topAnchor.constraint(equalTo: self.topAnchor, constant: 100),
    view.heightAnchor.constraint(equalToConstant: 300)
])

布局约束不起作用 iOS swift

Layout constraints are not working iOS swift

ios

nslayoutconstraint

swift