Ios 如何正确地向Swift中以编程方式创建的PDF添加密码？

目前，我正在以下一种方式创建我的PDF：

func drawPDFUsingPrintPageRenderer(printPageRenderer: UIPrintPageRenderer) -> NSData! {
    let data = NSMutableData()

    UIGraphicsBeginPDFContextToData(data, CGRect(x: 0, y: 0, width: A4PageHeight, height: A4PageWidth), nil)
    UIGraphicsBeginPDFPage()

    printPageRenderer.drawPage(at: 0, in: UIGraphicsGetPDFContextBounds())

    UIGraphicsEndPDFContext()

    return data
}

通过使用页面渲染器：

let printPageRenderer = CustomPrintPageRenderer()
let printFormatter = UIMarkupTextPrintFormatter(markupText: self.getHTML())
printPageRenderer.addPrintFormatter(printFormatter, startingAtPageAt: 0)

class CustomPrintPageRenderer: UIPrintPageRenderer {
let A4PageWidth: CGFloat = 595.2
let A4PageHeight: CGFloat = 841.8

var html: String?

override init() {
    super.init()

    // Specify the frame of the A4 page.
    let pageFrame = CGRect(x: 0.0, y: 0.0, width: A4PageHeight, height: A4PageWidth)

    // Set the page frame.
    self.setValue(NSValue(cgRect: pageFrame), forKey: "paperRect")

    // Set the horizontal and vertical insets (that's optional).
    self.setValue(NSValue(cgRect: pageFrame), forKey: "printableRect")
    self.setValue(1234, forKey: kCGPDFContextUserPassword as String)
    self.setValue(1234, forKey: kCGPDFContextOwnerPassword as String)
}

并尝试从以下数据创建PDF：

let pdfData = printPageRenderer.drawPDFUsingPrintPageRenderer(printPageRenderer: printPageRenderer)
mailComposer.addAttachmentData(pdfData as Data, mimeType: "application/pdf", fileName: "My PDF")

为页面渲染器创建新实例时：

let printPageRenderer = CustomPrintPageRenderer()
let printFormatter = UIMarkupTextPrintFormatter(markupText: self.getHTML())
printPageRenderer.addPrintFormatter(printFormatter, startingAtPageAt: 0)

class CustomPrintPageRenderer: UIPrintPageRenderer {
let A4PageWidth: CGFloat = 595.2
let A4PageHeight: CGFloat = 841.8

var html: String?

override init() {
    super.init()

    // Specify the frame of the A4 page.
    let pageFrame = CGRect(x: 0.0, y: 0.0, width: A4PageHeight, height: A4PageWidth)

    // Set the page frame.
    self.setValue(NSValue(cgRect: pageFrame), forKey: "paperRect")

    // Set the horizontal and vertical insets (that's optional).
    self.setValue(NSValue(cgRect: pageFrame), forKey: "printableRect")
    self.setValue(1234, forKey: kCGPDFContextUserPassword as String)
    self.setValue(1234, forKey: kCGPDFContextOwnerPassword as String)
}

我正试图通过以下方式设置密码：

self.setValue(1234, forKey: kCGPDFContextUserPassword as String)
self.setValue(1234, forKey: kCGPDFContextOwnerPassword as String)

但当我运行代码时，它会崩溃，并出现以下错误：

Terminating app due to uncaught exception 'NSUnknownKeyException', reason:  
setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key kCGPDFContextUserPassword.'

---

我做错了什么？我如何修复它？我在谷歌上搜索，但找不到任何有用的东西根据

UIGraphicsBeginPDFContextToData

的文档，最后一个参数是一个字典，它使用与

CGPDFContext

相同的辅助键

kCGPDFContextUserPassword

和

kCGPDFContextOwnerPassword

是这些辅助键之一

因此，您似乎需要在调用

UIGraphicsBeginPDFContextToData

时设置密码

let info: [AnyHashable: Any] = [kCGPDFContextUserPassword as String : "1234", kCGPDFContextOwnerPassword as String : "1234"]
UIGraphicsBeginPDFContextToData(data, CGRect(x: 0, y: 0, width: A4PageHeight, height: A4PageWidth), info)