ios - 为显示的 ViewController 设置约束

Question

我正在将 ViewController 推到我当前的 ViewController 之上。

我想推送的 ViewController 是一个 WebView，但我想这无关紧要。

我不希望呈现的 ViewController 位于状态栏下方。但是我该如何设置这些约束呢？

这是我加载推送的 ViewController 的代码:

@objc func loadWebView(sender: UIButton) {

        let vc = WebViewVC()

        webViewVC = vc

        self.present(webViewVC!, animated: true, completion: nil)

    }

如果我为 webViewVC.view 设置与父 ViewController 的 View 相关的约束，它当然会告诉我这是不允许的，因为 View 位于不同的 View 层次结构中。

这是我在 WebViewVC 中设置布局的方式:

func setUpView() {
        let view = UIView()
        self.view = view
        view.st(navigationBar,webView)

        navigationBar.heightAnchor.constraint(equalTo: webView.heightAnchor, multiplier: 0.1).isActive = true
        navigationBar.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 0).isActive = true
        navigationBar.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: 0).isActive = true
        navigationBar.topAnchor.constraint(equalTo: view.topAnchor, constant: 0).isActive = true
        navigationBar.bottomAnchor.constraint(equalTo: webView.topAnchor, constant: 0).isActive = true


        webView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 0).isActive = true
        webView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: 0).isActive = true
        webView.topAnchor.constraint(equalTo: navigationBar.bottomAnchor, constant: 0).isActive = true
        webView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: 0).isActive = true
    }

Answer 1

根据苹果文档:

The layout guide representing the portion of your view that is unobscured by bars and other content.

更改导航栏顶部 anchor :

if #available(iOS 11, *) {
     let guide = view.safeAreaLayoutGuide
     navigationBar.topAnchor.constraint(equalTo: guide.topAnchor).isActive = true

} else {
     navigationBar.topAnchor.constraint(equalTo: topLayoutGuide.bottomAnchor).isActive = true 
}