ios - 如何更改已经具有高度 anchor 的 UIView 的高度？

Question

如果我有一个 subview Controller :

autoCompleteViewController.view.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            autoCompleteViewController.view.topAnchor.constraint(equalTo: view.topAnchor, constant: 0),
            autoCompleteViewController.view.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 0),
            autoCompleteViewController.view.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: 0),
            autoCompleteViewController.view.bottomAnchor.constraint(equalTo: googleMapViewController.view.topAnchor, constant: 0),
            autoCompleteViewController.view.heightAnchor.constraint(equalToConstant: 44.0)
        ])

如何更改它的高度并更新 heightAnchor？我试过这个:

autoCompleteViewController
            .view
            .heightAnchor
            .constraint(equalToConstant: initialHeightAutoCompleteViewController + CGFloat(numberOfSuggestions * 45))
            .isActive = true

但没有运气。我还尝试添加 layoutIfNeeded() 和其他一些类似的方法，但没有用。如何使用 anchor 更新 View 高度？

Answer 1

除@Mukesh 之外，答案只是更新约束:

var heightAnchor:NSLayoutConstraint!

override func viewDidLoad() {
    super.viewDidLoad()
    heightAnchor = autoCompleteViewController.view.heightAnchor.constraint(equalToConstant:44.0)
    heightAnchor.isActive = true
}

func changeMyHeight(numberOfSuggestions: Int) {
    heightAnchor.constant = 44.0 + CGFloat(numberOfSuggestions * 45)
}

注意事项:

• 您不能在类级别完全声明此变量，因为 autoCompleteViewController.view 尚未实例化。
• 您不能同时设置约束和设置isActive = true。我总是遇到构建错误。