evaluateJavaScript快速为零

Question

请告诉我，我正在尝试从webview获取输入值。为什么我会得到"nil“。可能的问题是什么？下面提供的屏幕

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下面提供的代码

import SwiftUI
import WebKit

struct ContentView: View {
  var body: some View {
    WebView().edgesIgnoringSafeArea(.all)
  }
}

struct WebView: UIViewRepresentable {
  func makeUIView(context: Context) - > WKWebView {
    let webView = WKWebView()
    webView.scrollView.isScrollEnabled = false
    return webView
  }


  func updateUIView(_ webView: WKWebView, context: Context) {
    let liveView = "https://**/"
    if let url = URL(string: liveView) {
      let request = URLRequest(url: url)
      webView.load(request)
      webView.evaluateJavaScript("document.getElementById('ses').value") {
        (result, error) in
        print(result)
      }
    }
  }
}

Answer 1

您需要等待页面加载。

let timer = Timer.scheduledTimer(withTimeInterval: 5.0, repeats: true) {
  (timer) in
  webView.evaluateJavaScript("document.getElementById('ses').value") {
    (result, error) in
    print(result!)
  }
}

Answer 2

您的文档中似乎没有此元素。

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// element exists
console.log(document.getElementById('demo').value)

// element doesn't exist
console.log(document.getElementById('foo'))

<div id="demo" value="demo-value">Demo</div>

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