(Swift 2) PDF Signature Page Location

See more PDF Signatures Examples

This example demonstrates how to specify the location of a PDF signature on a page.

Note: This example requires Chilkat v9.5.0.85 or greater.

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func chilkatTest() {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    let pdf = CkoPdf()

    // Load a PDF to be signed.
    // The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
    var success: Bool = pdf.LoadFile("qa_data/pdf/hello.pdf")
    if success == false {
        print("\(pdf.LastErrorText)")
        return
    }

    // Options for signing are specified in JSON.
    let json = CkoJsonObject()

    // In most cases, the signingCertificateV2 and signingTime attributes are required.
    json.UpdateInt("signingCertificateV2", value: 1)
    json.UpdateInt("signingTime", value: 1)

    // When cryptographically signing a PDF, the signature's appearance can be placed on a specific
    // page in the PDF document, and at a specified location on the page.
    // The 1st page of the PDF document is page number 1 (we don't use 0-based numbering for PDF page numbers).
    // The PDF object has a NumPages property, so we can use it to sign on the last page of the PDF.
    json.UpdateInt("page", value: pdf.NumPages.intValue)

    // appearance.y and appearance.x JSON properties control the x,y location of the signature.
    // The "appearance.y" can be "top" or "bottom".
    // The "appearance.x" can be "left", "middle", or "right".
    // It is also possible to specify exact PDF location in user space coordinates, which is discussed below.
    json.UpdateString("appearance.y", value: "bottom")
    json.UpdateString("appearance.x", value: "middle")

    // In this example, the fontScale (in combination with the number of appearance text lines and the length of the longest text line),
    // automatically determine the width/height of the signature text box. Any included graphic (JPG image or built-in SVG) is automatically
    // scaled to fit. It is alternatively possible to specify the desired width/height of the signature rectangle.  In that case
    // you would NOT specify a fontScale because Chilkat would automatically chose a font scale to fit the text to the desired rectangle.
    // This example demonstrates how to specify the exact width/height of the PDF signature text box.
    json.UpdateString("appearance.fontScale", value: "9.0")

    json.UpdateString("appearance.text[0]", value: "Digitally signed by: cert_cn")
    json.UpdateString("appearance.text[1]", value: "current_dt")
    json.UpdateString("appearance.image", value: "document-accepted")
    json.UpdateString("appearance.imagePlacement", value: "left")
    json.UpdateString("appearance.imageOpacity", value: "100")

    // Load the signing certificate. (Use your own certificate.)
    let cert = CkoCert()
    success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx", password: "pfx_password")
    if success == false {
        print("\(cert.LastErrorText)")
        return
    }

    // Tell the pdf object to use the certificate for signing.
    success = pdf.SetSigningCert(cert)
    if success == false {
        print("\(pdf.LastErrorText)")
        return
    }

    success = pdf.SignPdf(json, outFilePath: "qa_output/hello_signed.pdf")
    if success == false {
        print("\(pdf.LastErrorText)")
        return
    }

    print("The PDF has been successfully cryptographically signed.")

    // The appearance of the signature appears in Adobe Acrobat as shown here:

    // ----------------------------------------------------------------------------------------------------
    // *** Scroll down for information about specifying the PDF signature x,y location in user space coordinates.
    // ----------------------------------------------------------------------------------------------------

    

    // The x,y coordinates of a PDF page are in "user space", called "points", and there are 72 pointes per inch.
    // A PDF page (8.5" x 11") is 612 points wide and 792 points high.
    // The bottom left is at 0,0.    The top right is at 612,792.
    // 
    // To specify the location of a signature rectangle, the "appearance.y" is the y coordinate of the top of the signature rectangle,
    // and the "appearance.x" is the x coordinate of the left of the signature rectangle.
    // Therefore, to position the signature rectangle at the exact top/left of the page, we do this:

    json.UpdateString("appearance.y", value: "792")
    json.UpdateString("appearance.x", value: "0")

    json.UpdateString("appearance.text[0]", value: "Digitally signed again by: cert_cn")
    json.UpdateString("appearance.text[1]", value: "current_dt")
    json.UpdateString("appearance.image", value: "document-accepted")
    json.UpdateString("appearance.imagePlacement", value: "right")

    let pdf2 = CkoPdf()
    success = pdf2.LoadFile("qa_output/hello_signed.pdf")
    success = pdf2.SetSigningCert(cert)

    success = pdf2.SignPdf(json, outFilePath: "qa_output/hello_signed2.pdf")
    if success == false {
        print("\(pdf2.LastErrorText)")
        return
    }

    print("The PDF has been successfully cryptographically signed again.")

    // Here we have the PDF with the signature just added at the exact top/left.
    

}