创建多页PDF

Question

我需要实现使用多页文本创建 pdf 的功能。

class PDFCreator {

func prepareData() -> Data {
    //1
    let pdfMetaData = [
      kCGPDFContextCreator: "PDF Creator",
      kCGPDFContextAuthor: "Pratik Sodha",
      kCGPDFContextTitle: "My PDF"
    ]

    //2
    let format = UIGraphicsPDFRendererFormat()
    format.documentInfo = pdfMetaData as [String: Any]

    //3
    let pageWidth = 8.5 * 72.0
    let pageHeight = 11 * 72.0
    let pageRect = CGRect(x: 0, y: 0, width: pageWidth, height: pageHeight)

    //4
    let renderer = UIGraphicsPDFRenderer(bounds: pageRect, format: format)

    //5
    let data = renderer.pdfData { (context) in
        //6
        context.beginPage()
        self.addText("Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.", pageRect: pageRect)

    }

    return data
}

@discardableResult
func addText(_ text : String, pageRect: CGRect) -> CGFloat {

    // 1
    let textFont = UIFont.systemFont(ofSize: 60.0, weight: .regular)

    // 2
    let paragraphStyle = NSMutableParagraphStyle()
    paragraphStyle.alignment = .natural
    paragraphStyle.lineBreakMode = .byWordWrapping

    // 3
    let textAttributes = [
        NSAttributedString.Key.paragraphStyle: paragraphStyle,
        NSAttributedString.Key.font: textFont
    ]
    let attributedText = NSAttributedString(string: text, attributes: textAttributes)
    let textSize = attributedText.boundingRect(with: pageRect.size, options: [.usesFontLeading, .usesLineFragmentOrigin], context: nil)

    // 4
    let textRect = CGRect(x: 10,
                          y: 10,
                          width: pageRect.width - 20,
                          height: textSize.height)

    attributedText.draw(in: textRect)

    return textRect.origin.y + textRect.size.height
  }
}

使用PDFCreator class 准备 pdf 数据并使用 PDFView 显示。

import UIKit
import PDFKit

class PDFPreviewViewController: UIViewController {

    //1
    @IBOutlet weak private var pdfView : PDFView!

    override func viewDidLoad() {

        super.viewDidLoad()

        //2
        let pdfData = PDFCreator().prepareData()

        //3
        pdfView.document = PDFDocument(data: pdfData)
        pdfView.autoScales = true
    }
}

实际 Output

除外 Output

整个文本将在 PDF 中，新的 PDF 页面不会减小字体大小。

非常感谢任何帮助。 谢谢你。

Answer 1

Output

使用CTFramesetterCreateFrame和CFAttributedStringGetLength

---

class PDFCreator {

lazy var pageWidth : CGFloat  = {
    return 8.5 * 72.0
}()

lazy var pageHeight : CGFloat = {
    return 11 * 72.0
}()

lazy var pageRect : CGRect = {
    CGRect(x: 0, y: 0, width: pageWidth, height: pageHeight)
}()

lazy var marginPoint : CGPoint = {
    return CGPoint(x: 10, y: 10)
}()

lazy var marginSize : CGSize = {
    return CGSize(width: self.marginPoint.x * 2 , height: self.marginPoint.y * 2)
}()


func prepareData() -> Data {
    //1
    let pdfMetaData = [
      kCGPDFContextCreator: "PDF Creator",
      kCGPDFContextAuthor: "Pratik Sodha",
      kCGPDFContextTitle: "My PDF"
    ]

    //2
    let format = UIGraphicsPDFRendererFormat()
    format.documentInfo = pdfMetaData as [String: Any]

    //3
    let renderer = UIGraphicsPDFRenderer(bounds: pageRect, format: format)

    //5
    let data = renderer.pdfData { (context) in

        //6
        self.addText("Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.", context: context)
    }

    return data
}

@discardableResult
func addText(_ text : String, context : UIGraphicsPDFRendererContext) -> CGFloat {

    // 1
    let textFont = UIFont.systemFont(ofSize: 60.0, weight: .regular)

    // 2
    let paragraphStyle = NSMutableParagraphStyle()
    paragraphStyle.alignment = .natural
    paragraphStyle.lineBreakMode = .byWordWrapping

    // 3
    let textAttributes = [
        NSAttributedString.Key.paragraphStyle: paragraphStyle,
        NSAttributedString.Key.font: textFont
    ]

    //4
    let currentText = CFAttributedStringCreate(nil,
                                               text as CFString,
                                               textAttributes as CFDictionary)
    //5
    let framesetter = CTFramesetterCreateWithAttributedString(currentText!)

    //6
    var currentRange = CFRangeMake(0, 0)
    var currentPage = 0
    var done = false
    repeat {

        //7
        /* Mark the beginning of a new page.*/
        context.beginPage()

        //8
        /*Draw a page number at the bottom of each page.*/
        currentPage += 1
        drawPageNumber(currentPage)


        //9
        /*Render the current page and update the current range to
          point to the beginning of the next page. */
        currentRange = renderPage(currentPage,
                                  withTextRange: currentRange,
                                  andFramesetter: framesetter)

        //10
        /* If we're at the end of the text, exit the loop. */
        if currentRange.location == CFAttributedStringGetLength(currentText) {
            done = true
        }

    } while !done

    return CGFloat(currentRange.location + currentRange.length)
}

func renderPage(_ pageNum: Int, withTextRange currentRange: CFRange, andFramesetter framesetter: CTFramesetter?) -> CFRange {
    var currentRange = currentRange
    // Get the graphics context.
    let currentContext = UIGraphicsGetCurrentContext()

    // Put the text matrix into a known state. This ensures
    // that no old scaling factors are left in place.
    currentContext?.textMatrix = .identity

    // Create a path object to enclose the text. Use 72 point
    // margins all around the text.
    let frameRect = CGRect(x: self.marginPoint.x, y: self.marginPoint.y, width: self.pageWidth - self.marginSize.width, height: self.pageHeight - self.marginSize.height)
    let framePath = CGMutablePath()
    framePath.addRect(frameRect, transform: .identity)

    // Get the frame that will do the rendering.
    // The currentRange variable specifies only the starting point. The framesetter
    // lays out as much text as will fit into the frame.
    let frameRef = CTFramesetterCreateFrame(framesetter!, currentRange, framePath, nil)

    // Core Text draws from the bottom-left corner up, so flip
    // the current transform prior to drawing.
    currentContext?.translateBy(x: 0, y: self.pageHeight)
    currentContext?.scaleBy(x: 1.0, y: -1.0)

    // Draw the frame.
    CTFrameDraw(frameRef, currentContext!)

    // Update the current range based on what was drawn.
    currentRange = CTFrameGetVisibleStringRange(frameRef)
    currentRange.location += currentRange.length
    currentRange.length = CFIndex(0)

    return currentRange
}

func drawPageNumber(_ pageNum: Int) {

    let theFont = UIFont.systemFont(ofSize: 20)

    let pageString = NSMutableAttributedString(string: "Page \(pageNum)")
    pageString.addAttribute(NSAttributedString.Key.font, value: theFont, range: NSRange(location: 0, length: pageString.length))

    let pageStringSize =  pageString.size()

    let stringRect = CGRect(x: (pageRect.width - pageStringSize.width) / 2.0,
                            y: pageRect.height - (pageStringSize.height) / 2.0 - 15,
                            width: pageStringSize.width,
                            height: pageStringSize.height)

    pageString.draw(in: stringRect)

}
}

使用 PDFCreator class 准备 pdf 数据并使用 PDFView 显示。

import UIKit
import PDFKit

class PDFPreviewViewController: UIViewController {

    //1
    @IBOutlet weak private var pdfView : PDFView!

    override func viewDidLoad() {

        super.viewDidLoad()

        //2
        let pdfData = PDFCreator().prepareData()

        //3
        pdfView.document = PDFDocument(data: pdfData)
        pdfView.autoScales = true
    }
}

Answer 2

答案非常鼓舞人心。 但我还需要使用不同的 styles 渲染文本，所以为了重用您的代码，我将renderPage(_:withTextRange:andFramesetter)更改为renderPage(_:withTextRange:andFramesetter:from) ：

func renderPage(_ pageNum: Int, withTextRange currentRange: CFRange, andFramesetter framesetter: CTFramesetter?, from lastPosition: CGFloat = 0) -> CFRange {
    var currentRange = currentRange
    let currentContext = UIGraphicsGetCurrentContext()
    currentContext?.textMatrix = .identity

    // MARK: - Chanages1: Resize rect based on the last ending point
    let frameRect = CGRect(
        x: self.marginPoint.x, 
        y: self.marginPoint.y + lastPosition, 
        width: self.pageWidth - self.marginSize.width, 
        height: self.pageHeight - self.marginSize.height - lastPosition
        )

    let framePath = CGMutablePath()
    framePath.addRect(frameRect)
    let frameRef = CTFramesetterCreateFrame(framesetter!, currentRange, framePath, nil)

    // MARK: - Changes2
    if lastPosition == 0 {
        currentContext?.translateBy(x: 0, y: self.pageHeight)

        currentContext?.scaleBy(x: 1.0, y: -1.0)
    } else {
        // MARK: - Already in the context, no need to "mirror"
        currentContext?.translateBy(x: 0, y: -lastPosition)
    }
    CTFrameDraw(frameRef, currentContext!)
    currentRange = CTFrameGetVisibleStringRange(frameRef)
    currentRange.location += currentRange.length
    currentRange.length = CFIndex(0)

    return currentRange
}

和addText(_:context)到add(_:font:in:at:from)

func add(_ text: String,
               font: UIFont,
               in context: UIGraphicsPDFRendererContext,
               at currentPage: Int,
               from lastPosition: CGFloat = 0) -> (Int, CGFloat) {
    // ...
    var lastPosition = lastPosition
    var newPosition: CGFloat = 0
    repeat {
        // ...
        // MARK: - Changes1: text left needed to fill
        let textRect = CTFramesetterSuggestFrameSizeWithConstraints(
            framesetter, currentRange, nil, 
            .init(
                width: self.pageWidth - self.marginSize.width, 
                height: self.pageHeight - self.marginSize.height - lastPosition
                ), 
            nil
            )

        currentRange = renderPage(2, withTextRange: currentRange, andFramesetter: framesetter, from: lastPosition)

        // MARK: - Changes2: reset after first drawing
        lastPosition = 0
        // MARK: - save the newPosition
        newPosition = textRect.height > newPosition ? textRect.height : newPosition
        // ...
    } while !done

    return (currentPage, newPosition)
}

现在，在prepareData我可以添加具有不同 styles 的文本，如下所示：

let data = renderer.pdfData { (context) in
    context.beginPage()
    drawPageNumber(1)
    var lastGroup: (Int, CGFloat)
    lastGroup = add(body, font: .systemFont(ofSize: 23), in: context, at: 1)

    lastGroup = add(body, font: .systemFont(ofSize: 33), in: context, at: lastGroup.0, from: lastGroup.1)
    lastGroup = add(body, font: .systemFont(ofSize: 43), in: context, at: lastGroup.0, from: lastGroup.1)
    lastGroup = add(body, font: .systemFont(ofSize: 53), in: context, at: lastGroup.0, from: lastGroup.1)
}

---

更新

以前的版本仅在文本超过页面高度时才有效。 绘制较短的文本会很乱。 这次我保留了最后一次绘图完成的 position。

这是更新的版本：

// MARK: - lazy vars
lazy var maxTextBounds: CGSize = {
        return CGSize(width: pageWidth - marginSize.width,
                      height: pageHeight - marginSize.height)
    }()
    lazy var cgContext: CGContext = {
        print("getting cgContext")
        let context = UIGraphicsGetCurrentContext()!
        context.textMatrix = .identity
        // MARK: - flip context
        context.translateBy(x: 0, y: pageHeight)
        context.scaleBy(x: 1, y: -1)
        return context
    }()

// MARK: - Render page
func renderPage(_ pageNum: Int, withTextRange currentRange: CFRange, andFramesetter framesetter: CTFramesetter?, from lastPosition: CGFloat = 0) -> (CFRange, CGFloat) {


        // MARK: - text height in current page
        let textBounds = CTFramesetterSuggestFrameSizeWithConstraints(framesetter!,
                                                                      currentRange,
                                                                      nil,
                                                                      .init(width: maxTextBounds.width, height: maxTextBounds.height - lastPosition),
                                                                      nil)

        if maxTextBounds.height == lastPosition {
            // not enough space in this page
            // MARK: - reset
            return (currentRange, 0)
        }
        // MARK: - path where text drawn at
        let framePath = CGMutablePath()
        // MARK: - invisble rect surrounds the text, when drawing the rect will be move to marginPoint
        framePath.addRect(CGRect(origin: .zero, size: textBounds))

        // MARK: - text frame
        let frameRef = CTFramesetterCreateFrame(framesetter!, currentRange, framePath, nil)

        // MARK: - move up
        print("move up by", pageHeight - (textBounds.height + lastPosition + marginPoint.y))
        cgContext.translateBy(x: marginPoint.x, y: pageHeight - (textBounds.height + lastPosition + marginPoint.y))
        // MARK: - draw
        CTFrameDraw(frameRef, cgContext)
        // MARK: - move back for next
        cgContext.translateBy(x: -marginPoint.x, y: -pageHeight + (textBounds.height + lastPosition + marginPoint.y))

        // MARK: - udpate current range
        var currentRange = currentRange
        currentRange = CTFrameGetVisibleStringRange(frameRef)
        currentRange.location += currentRange.length
        currentRange.length = CFIndex(0)

        // MARK: - updating the succeeding position
        var newPosition = textBounds.height + lastPosition
        if newPosition >= pageHeight - marginSize.height {
            newPosition = 0
        }
        return (currentRange, newPosition)
    }

当文本太长而无法放入当前页面时， add(_:font:in:at:from)会重复调用renderPage(_:withTextRange:andFramesetter:from) ，在它发生之前，我们需要“重置”上下文.

// in else block
context.beginPage()
currentPage += 1

drawPageNumber(currentPage)
lastPosition = 0
// MARK: - new Page, reset context for those texts not finished drawing
cgContext.textMatrix = .identity
cgContext.translateBy(x: 0, y: pageHeight)
cgContext.scaleBy(x: 1, y: -1)

Answer 3

类似于 Pratik Sodha 的答案，但使用 TextKit，而不是 CoreText。 这样做的主要优点是 TextKit 完全支持NSAttributedString ，而不是CFAttributedString 。 这意味着我现在可以将NSTextAttachment CFAttributedString支持的文本中。

class AttributedStringToPDFConverter {
    
    lazy var pageWidth : CGFloat  = {
        return 8.5 * 72.0
    }()
    
    lazy var pageHeight : CGFloat = {
        return 11 * 72.0
    }()
    
    lazy var pageRect : CGRect = {
        CGRect(x: 0, y: 0, width: pageWidth, height: pageHeight)
    }()
    
    lazy var marginPoint : CGPoint = {
        return CGPoint(x: 50, y: 50)
    }()
    
    lazy var marginSize : CGSize = {
        return CGSize(width: self.marginPoint.x * 2 , height: self.marginPoint.y * 2)
    }()
    
    func pdfData(from attributedString: NSAttributedString) -> Data {
        let pdfMetaData = [
            kCGPDFContextCreator: "...",
            kCGPDFContextTitle: "..."
        ]
        let format = UIGraphicsPDFRendererFormat()
        format.documentInfo = pdfMetaData as [String: Any]
        let renderer = UIGraphicsPDFRenderer(bounds: pageRect, format: format)
        
        let data = renderer.pdfData { (context) in
            self.addText(attributedString, context: context)
        }
        
        return data
    }
    
    private func addText(_ text : NSAttributedString, context : UIGraphicsPDFRendererContext) {
        let layoutManager = NSLayoutManager()
        let textStorage = NSTextStorage()
        textStorage.append(text)
        textStorage.addLayoutManager(layoutManager)
        let textContainerSize = CGSize(width: pageWidth - marginSize.width, height: pageHeight - marginSize.height)
        var textContainer: NSTextContainer
        var textViews = [UITextView]()
        
        // keep adding text containers and text views...
        repeat {
            textContainer = NSTextContainer(size: textContainerSize)
            textViews.append(UITextView(frame: CGRect(origin: marginPoint, size: textContainerSize), textContainer: textContainer))
            layoutManager.addTextContainer(textContainer)
        // while the last glyph is not in a text container
        } while layoutManager.textContainer(forGlyphAt: layoutManager.numberOfGlyphs - 1, effectiveRange: nil) == nil
        
        // draw each text view
        for textView in textViews {
            context.beginPage()
            context.cgContext.translateBy(x: marginPoint.x, y: marginPoint.y)
            textView.layer.render(in: context.cgContext)
        }
    }
}