设置WKWebView的scrollView的contentInset导致页面跳转到顶部

Question

设置后contentInset，WKWebView我发现如果我使用默认的滑动手势在页面之间导航，WKWebView将不会保留contentInset并直接跳转到顶部，有人知道如何解决吗？谢谢！

我的示例代码：

import UIKit
import WebKit

class ViewController: UIViewController {

    private lazy var webView: WKWebView = {
        let view = WKWebView(frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height))
        view.allowsBackForwardNavigationGestures = true
        view.scrollView.contentInsetAdjustmentBehavior = .never
        view.scrollView.contentInset = UIEdgeInsets(top: 50, left: 0, bottom: 0, right: 0)

        view.navigationDelegate = self
        return view
    }()

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        self.view.addSubview(self.webView)

        if let url = URL(string: "http://www.wikipedia.org") {
            self.webView.load(URLRequest(url: url))
        }
    }

}

Answer 1

如果为 WKWebView 的滚动视图设置 contentInset，则需要为 WKWebview 的另一个属性设置相同的值。 view.setValue(UIEdgeInsets, forKey: "_obscuredInsets")

请参阅：https://opensource.apple.com/source/WebKit2/WebKit2-7600.1.4.11.10/ChangeLog

private lazy var webView: WKWebView = {
        let view = WKWebView(frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height))
        view.allowsBackForwardNavigationGestures = true
        view.scrollView.contentInsetAdjustmentBehavior = .never
        let edgeInsets = UIEdgeInsets(top: 50, left: 0, bottom: 0, right: 0)
        view.setValue(edgeInsets, forKey: "_obscuredInsets")
        view.scrollView.contentInset = edgeInsets
        return view
    }()

如果设置 contentInsetAdjustmentBehavior = .automatic，状态栏会有额外的边缘。您还需要将状态栏高度添加到observedInsets。

view.scrollView.contentInsetAdjustmentBehavior = . automatic
webView.scrollView.contentInset = UIEdgeInsets(top: 50, left: 0, bottom: 0, right: 0)
webView.setValue(UIEdgeInsets(top: 50 + 44, left: 0, bottom: 0, right: 0), forKey: "_obscuredInsets")

44是状态栏（safeArea）的高度。

检查了最新的WKWebView：https://github.com/WebKit/webkit/blob/master/Source/WebKit/UIProcess/API/Cocoa/WKWebView.mm

现在需要添加一个额外的属性：_haveSetObscuredInsets

webView.setValue(true, forKey: "_haveSetObscuredInsets")