问题

我有一个基本的模型，像这样：
```swift
public final class WebSite: ObservableObject {
    @Published
    var URL: String
    // 让我们假设这将是一个有效的 URL
}

和一个 webview。它使用站点 URL 来呈现一个 UIViewRepresentable（我的站点视图必须是一个类，因为 WKWebView 协议）：

class WebSiteWebView: WKWebView {
    @ObservedObject
    var webSite: WebSite

    init() { /* 初始化。这里不相关 */ }

    func loadUrl(url: String) {
        self.load(URLRequest(url: URL(string: url)!))
    }

    func render() -> some View {
        let representable = WebSiteWebView.Representable(webView: self)
        
        do {
            try representable.webView.loadUrl(url: self.webSite.URL)
        } catch { ... }
    }
}

现在，我有一个父 ContentView 如下：

struct ContentView: View {
    @StateObject var webSite: WebSite = WebSite(URL: "stackoverflow.com")

    var body: some View {
        WebSiteView(webSite: webSite)
    }
}

和一个显示 web 视图的 WebSiteView：

struct WebSiteView: View {
    @ObservedObject
    var webSite: WebSite
    
    var body: some View {
        let webView: WebSiteWebView = WebView(webSite: webSite)

        VStack {
            webView.render()

            Button("Switch URL") {
                webSite.URL = "google.com"
            }
        }
    }
}

为了完整性，UIViewRepresentable 的实现：

extension WebSiteWebView {
    struct Representable: UIViewRepresentable {
        let webView: WebSiteWebView

        func makeUIView(context: Context) -> WebSiteWebView {
            self.webView
        }

        func updateUIView(_ uiView: WebSiteWebView, context: Context) {}
    }
}

简而言之，发生了以下情况：

1. 父 ContentView 初始化一个包含名为 URL 的发布的 String 的 @StateObject。
2. ContentView 有一个名为 WebSiteView 的子视图，将网站类作为 @ObservedObject。
3. 该子视图从 @ObservedObject 加载 URL。
4. 该子视图还有一个更改 URL 的按钮。

我期望在按下按钮后，WebSiteView 将重新渲染，因为它将 webSite 声明为 @ObservedObject。而且它确实（从技术上）做到了。webView.render() 使用新的 URL 调用，但 WKWebView 不会刷新。有人知道这是为什么吗？

<details>
<summary>英文:</summary>

I have a basic model like this&quot;

public final class WebSite: ObservableObject {
@Published
var URL: String
// Let us please assume that this will be a valid URL
}

And a webview. It uses the site url to render a `UIViewRepresentable` (my site view must be a class bc of the `WKWebView` protocol):

class WebSiteWebView: WKWebView {
@ObservedObject
var webSite: WebSite

init() { /* initialization. Not relevant here*/ }

loadUrl(url: String) {
    self.load(URLRequest(url: url))
}

render() -> some View {
    let representable = WebSiteWebView.Representable(webView: self)
    
    do {
        try representable.webView.loadUrl(url: self.webSite.url)
    } catch { ... }
}

}

Now, I have a parent ContentView as follows:

struct ContentView: View {
@StateObject var webSite: WebSite = WebSite(URL: "stackoverflow.com")

var body: some View {
    WebSiteView(webSite: webSite)
}

}

and a `WebSiteView` that displays a web view:

struct WebSiteView: View {
@ObservedObject
var webSite: WebSite

var body: some View {
    let webView: WebSiteWebView = WebView(webSite: webSite)

    VStack {
        webView.render()

        Button("Switch URL") {
            webSite.URL = "google.com"
        }
    }
}

}

The `UIViewRepresentable` impl for completeness

extension WebSiteWebView {
struct Representable: UIViewRepresentable {
let webView: WebSiteWebView

    func makeUIView(context: Context) -> WebSiteWebView {
        self.webView
    }

    func updateUIView(_ uiView: WebSiteWebView, context: Context) {}
}

}

In a nutshell, this is what's going on:
1. The parent ContentView initializes a `@StateObject` that contains a published `String` named `URL`.
2. The ContentView has a child view named `WebSiteView` that takes the web site class as an `@ObservedObject`
3. That child view loads the `URL` from the `@ObservedObject`
4. That child view also has a button that changes the `URL`

I would expect that after the button is pressed, the `WebSiteView` would re-render, since it declares the `webSite` as an `@ObservedObject`. And, it does (technically). `webView.render()` is called with the new `URL` but the `WKWebView` does not refresh. Does anyone know why this is happening?

</details>


# 答案1
**得分**: 1

代码部分如下：

```swift
struct WebSiteWebView: UIViewRepresentable {
    let url: URL

    func makeUIView(context: Context) -> WKWebView {
        WKWebView()
    }

    func updateUIView(_ uiView: WKWebView, context: Context) {
        if uiView.url != url {
            uiView.load(url)
        }
    }
}

    struct WebSiteWebView: UIViewRepresentable {
        let url: URL

        func makeUIView(context: Context) -> WKWebView {
            WKWebView()
        }

        func updateUIView(_ uiView: WKWebView, context: Context) {
            if uiView.url != url {
                uiView.load(url)
            }
        }
    }