ios - 无法使用 PDFKit 添加图像并保存到 pdf 文件

Question

我有一个类可以通过将图像插入 pdf 并使用插入的图像保存新的 pdf 来编辑 pdf。

下面的代码是我用来实现场景的方式，通过创建自定义PDFAnnotation. 我将 type 指定为，.widget而不是.stamp避免在对角线上绘制黑线。

final private class PDFImageAnnotation: PDFAnnotation {

    var image: UIImage?

    convenience init(_ image: UIImage?, bounds: CGRect, properties: [AnyHashable: Any]?) {
        self.init(bounds: bounds, forType: PDFAnnotationSubtype.widget, withProperties: properties)
        self.image = image
    }

    override func draw(with box: PDFDisplayBox, in context: CGContext) {
        super.draw(with: box, in: context)

        // Drawing the image within the annotation's bounds.
        guard let cgImage = image?.cgImage else { return }
        context.draw(cgImage, in: bounds)
    }
}

以下是我如何显示 pdf 并选择要保存为 pdf 的图像

private func setupPDF() {
    guard let url = url else { return }
    pdfView.document = PDFDocument(url: url)
    pdfView.autoScales = true
}

private func addImageAndSave(_ image: UIImage) {
    guard let page = pdfView.currentPage else { return }

    let pageBounds = page.bounds(for: .cropBox)
    let imageBounds = CGRect(x: pageBounds.midX, y: pageBounds.midY, width: image.size.width, height: image.size.height)
    let imageStamp = PDFImageAnnotation(image, bounds: imageBounds, properties: nil)
    imageStamp.shouldDisplay = true
    imageStamp.shouldPrint = true
    page.addAnnotation(imageStamp)

    // Save PDF with image
    let fileName = url.lastPathComponent
    let saveUrl = FileManager.default.temporaryDirectory.appendingPathComponent(fileName, isDirectory: false)
    pdfView.document?.write(to: saveUrl)
}

但是结果pdf文件如下

右栏中的预览确实显示了图片，但是当在Preview应用程序或任何浏览器中打开 pdf 时，图片不存在。

如何使图片出现在最终的 pdf 文件中？

谢谢。

Answer 1

我还必须绘制该图像PDFPage以使它们出现在保存的 pdf 文件中

final private class ImagePDFPage: PDFPage {

    /// A flag indicates whether to draw image on a page
    /// 
    /// - Note: Set this to `true` before write pdf to file otherwise the image will not be appeared in pdf file
    var saveImageToPDF: Bool = false

    private var imageAnnotation: EkoPDFImageAnnotation? = nil


    func addImageAnnotation(_ annotation: EkoPDFImageAnnotation) {
        imageAnnotation = annotation
        addAnnotation(annotation)
    }

    func removeImageAnnotation() {
        guard let imageAnnotation = imageAnnotation else { return }
        self.imageAnnotation = nil
        removeAnnotation(imageAnnotation)
    }

    override func draw(with box: PDFDisplayBox, to context: CGContext) {
        super.draw(with: box, to: context)

        guard saveImageToPDF,
              let annotation = imageAnnotation,
              let cgImage = annotation.image?.cgImage else { return }
        context.draw(cgImage, in: annotation.bounds)
    }
}

并更新PDFDocument.delegate以告知ImagePDFPage用作 pdf 页面的类

extension PDFEditorViewController: PDFDocumentDelegate {
    func classForPage() -> AnyClass {
        return ImagePDFPage.self
    }
}

结果