Swift中的WKWebView印刷忽略背景

Question

我尝试将HTML代码打印到具有以下代码的PDF上：

class PDFPrinter: NSObject, WKNavigationDelegate {
    
    static var shared = PDFPrinter()
    let webView = WKWebView()
    private var saveURL: URL!
    private var completion: () -> () = {}
    
    override init() {
        super.init()
        self.webView.navigationDelegate = self
    }
    
    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        let printInfo = NSPrintInfo(dictionary: [
            .paperSize: CGSize(width: 595.28, height: 841.89),
            .jobDisposition: NSPrintInfo.JobDisposition.save,
            .jobSavingURL: self.saveURL!,
        ])
        printInfo.horizontalPagination = .automatic
        printInfo.verticalPagination = .automatic
        let margin = 20.0
        printInfo.leftMargin = margin
        printInfo.topMargin = margin
        printInfo.rightMargin = margin
        printInfo.bottomMargin = margin
        let pro = self.webView.printOperation(with: printInfo)
        pro.showsPrintPanel = false
        pro.showsProgressPanel = false
        let selector = #selector(self.printOperationDidRun(printOperation: success: contextInfo:))
        pro.runModal(for: NSWindow(), delegate: self, didRun: selector, contextInfo: nil)
    }
    
    func printHTML(htmlString: String, saveURL: URL, completion: @escaping () -> ()) {
        self.saveURL = saveURL
        self.completion = completion
        webView.loadHTMLString(htmlString, baseURL: nil)
    }
    
    @objc func printOperationDidRun( printOperation: NSPrintOperation,
                                     success: Bool,
                                     contextInfo: UnsafeMutableRawPointer?){
        self.completion()
    }
    
}

此功能除了一件事：HTML的背景完全忽略了，我的PDF总是完全白色。我找不到wkwebview，nsprintinfo或nsprintoperation如何更改它的设置。有什么想法吗？

Answer 1

我遇到了同样的问题（似乎iOS 16.4带有类似的问题），经过数小时的尝试解决，看来该CSS指令为我解决了：

@media print {
* {
    -webkit-print-color-adjust: exact !important;
  }
}

Answer 2

在 iOS 16 或以上版本编译器跳过 css 一部分您必须告诉他们这是重要

将此代码放在html文件中或在您的CSS中

<style>
    @media print {
    * {
        -webkit-print-color-adjust: exact !important;
      }
    }
</style>