UIMarkupTextPrintFormatter 和 Mac Catalyst

Question

我有一个 iPad 应用程序，我已经使用 Catalyst 成功地将它迁移到了 Mac。

虽然我可以在 iPad/iPhone 上使用 生成 PDF UIMarkupTextPrintFormatter，但它在 Mac 上无法正常工作。

事实上，我什至无法构建 Mac 二进制文件，除非我注释掉UIMarkupTextPrintFormatterusing #if !targetEnvironment(macCatalyst)as Xcode 只会显示一个错误：

体系结构 x86_64 的未定义符号：
“_OBJC_CLASS_$_UIMarkupTextPrintFormatter”，引用自：Functions.o ld 中的 objc-class-ref：未找到体系结构 x86_64 clang 的符号：错误：链接器命令失败，退出代码为 1（使用 -v查看调用）

这令人困惑，因为 Apple 的文档表明它与 Mac Catalyst 13.0+ https://developer.apple.com/documentation/uikit/uimarkuptextprintformatter兼容

有没有其他人遇到过这种情况，您是否能够找到解决方案？

谢谢你。

编辑：我找到了一个很好的解决方案，它也可以在 macCatalyst 中运行而无需修改，基于 Sam Wize 的帖子：

https://samwize.com/2019/07/02/how-to-generate-pdf-with-images/

关键是使用 WKWebView 对象（但不显示它）作为加载 HTML 文件的中介，然后使用它的 viewPrintFormatter 通过其didFinish navigation:委托呈现 PDF

这是我的代码（希望注释是不言自明的）。使用以下代码创建一个名为 PDFCreator.swift 的 Swift 文件：

import WebKit

typealias PDFCompletion = (Result<NSData, Error>) -> Void

class PDFCreator: NSObject {
var webView: WKWebView? = nil
var completion: PDFCompletion!

func exportPDF(html: String, completion: @escaping PDFCompletion) throws {
    // Set up the completion handler to be called by the function in the delegate method
    // It has to be instantiated here so the delegate method can access it
    self.completion = completion
    // Creates a WebKit webView to load the HTML string & sets the delegate (self) to respond
    let webView = WKWebView()
    webView.navigationDelegate = self
    // If the other assets are in the same baseURL location (eg. Temporary Documents Directory, they will also render)
    // But you need to ensure the assets are already there before calling this function
    let baseURL = URL(fileURLWithPath: NSTemporaryDirectory())
    // Loads the HTML string into the WebView and renders it (invisibly) with any assets
    webView.loadHTMLString(html, baseURL: baseURL)
    self.webView = webView
    // After this function closes, the didFinish navigation delegate method is called
    }


func createPDF(_ formatter: UIViewPrintFormatter) {
    // Subclass UIPrintPageRenderer if you want to add headers/footers, page counts etc.
    let printPageRenderer = UIPrintPageRenderer()
    printPageRenderer.addPrintFormatter(formatter, startingAtPageAt: 0)

    // Assign paperRect and printableRect
    // A4, 72 dpi
    let paperRect = CGRect(x: 0, y: 0, width: 595.2, height: 841.8)
    let padding: CGFloat = 20
    let printableRect = paperRect.insetBy(dx: padding, dy: padding)
    printPageRenderer.setValue(printableRect, forKey: "printableRect")
    printPageRenderer.setValue(paperRect, forKey: "paperRect")
    // Assign header & footer dimensions
    printPageRenderer.footerHeight = 70
    printPageRenderer.headerHeight = 20

    // Create PDF context and draw
    let pdfData = NSMutableData()
    UIGraphicsBeginPDFContextToData(pdfData, .zero, nil)
    for i in 0..<printPageRenderer.numberOfPages {
        UIGraphicsBeginPDFPage();
        printPageRenderer.drawPage(at: i, in: UIGraphicsGetPDFContextBounds())
    }
    UIGraphicsEndPDFContext();

    // Send the PDF data out with a Result of 'success' & the NSData object for processing in the completion block
    self.completion?(.success(pdfData))
    }
}


extension PDFCreator: WKNavigationDelegate {
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
    let viewPrintFormatter = webView.viewPrintFormatter()
    createPDF(viewPrintFormatter)
    }
}

在我的应用程序中，我实例化了一个 PDFCreator 对象

let pdfCreator = PDFCreator()

然后我确保首先在相同的“baseURL”位置创建 HTML 文件所需的所有本地资产 - 在我的情况下NSTemporaryDirectory()- 然后运行以下命令：

let pdfFilePath = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent("test.pdf")

 try? pdfCreator.exportPDF(html: htmlString, completion: { (result) in
         switch result {
         case .success(let data):
                try? data.write(to: pdfFilePath, options: .atomic)
                // *** Do stuff with the file at pdfFilePath ***

         case .failure(let error):
                print(error.localizedDescription)
            }
        })

Answer 1

我也有同样的问题。但我能够通过使用 Swift 的函数将 html 转换为属性文本，然后将 UISimpleTextPrintFormatter 与属性文本一起使用来解决这个问题。

我原来的代码：

let formatter = UIMarkupTextPrintFormatter(markupText: htmlString)
formatter.perPageContentInsets = UIEdgeInsets(top: 70.0, left: 60.0, bottom: 70.0, right: 60.0)
printController.printFormatter = formatter
printController.present(animated: true, completionHandler: nil)

使用 Catalyst（和 iOS）：

guard let printData = htmlString.data(using: String.Encoding.utf8) else { return }
do {
    let printText =  try NSAttributedString(data: printData, options: [.documentType: NSAttributedString.DocumentType.html,  .characterEncoding: String.Encoding.utf8.rawValue],  documentAttributes: nil)
        
    let formatter = UISimpleTextPrintFormatter(attributedText: printText)
    formatter.perPageContentInsets = UIEdgeInsets(top: 70.0, left: 60.0, bottom: 70.0, right: 60.0)
    printController.printFormatter = formatter
    printController.present(animated: true, completionHandler: nil)
} catch {
     print(error)
}

然而，NSAttributedString(data:) 似乎对你在 Catalyst 上输入的内容比在 iOS 上更敏感。例如，我在 iOS 上运行良好的表格是否有问题？所以这不是一个完美的解决方案。

编辑 似乎可以更好地处理例如表的更好的解决方案是：

func compHandler(attributedString:NSAttributedString?, attributeKey:[NSAttributedString.DocumentAttributeKey : Any]?, error:Error?) -> Void {
    guard let printText = attributedString else { return }
    let formatter = UISimpleTextPrintFormatter(attributedText: printText)
    formatter.perPageContentInsets = UIEdgeInsets(top: 70.0, left: 60.0, bottom: 70.0, right: 60.0)
    printController.printFormatter = formatter
    printController.present(animated: true, completionHandler: nil)
}
        
guard let printData = htmlString.data(using: String.Encoding.utf8) else { return }
NSAttributedString.loadFromHTML(data: printData, options: [.documentType: NSAttributedString.DocumentType.html,  .characterEncoding: String.Encoding.utf8.rawValue], completionHandler: compHandler)