(Swift 2) PDF Signature with Background Image (Seal/Stamp/etc.)

See more PDF Signatures Examples

Demonstrates how to sign a PDF with an appearance that includes a background image, such as a seal, stamp, etc.

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)

    // Put the signature on page 1, top left
    json.UpdateInt("page", value: 1)
    json.UpdateString("appearance.y", value: "top")
    json.UpdateString("appearance.x", value: "left")

    // Use a font scale of 10.0
    json.UpdateString("appearance.fontScale", value: "10.0")

    // In this example, the appearance of the digital signature will contain three lines:
    // 1) The signing certificate's common name
    // 2) The current date/time
    // 3) Some arbitrary text.
    // The keyword "cert_cn" is replaced with the Certificate's Subject Common Name.
    // The keyword "current_dt" is replaced with the current date/time.
    // Any number of appearance text lines can be added.
    json.UpdateString("appearance.text[0]", value: "Digitally signed by: cert_cn")
    json.UpdateString("appearance.text[1]", value: "current_dt")
    json.UpdateString("appearance.text[2]", value: "The crazy brown fox jumps over the lazy dog.")

    // Load a JPG image to be shown with 30% opacity in the background.
    // (the image must be in the JPG format)
    // The sample university.jpb is available at https://example-code.com/images/university.jpg

    let jpgData = CkoBinData()
    success = jpgData.LoadFile("qa_data/jpg/university.jpg")
    if success == false {
        print("Failed to load the JPG image.")
        return
    }

    success = pdf.SetSignatureJpeg(jpgData)
    if success == false {
        print("\(pdf.LastErrorText)")
        return
    }

    // Specify that we want to display the JPG image in the center with 30% opacity.
    json.UpdateString("appearance.image", value: "custom-jpg")
    json.UpdateString("appearance.imagePlacement", value: "center")
    json.UpdateString("appearance.imageOpacity", value: "30")

    // Load the signing certificate. (Use your own certificate.)
    let cert = CkoCert()
    success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx", password: "secret")
    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 below.
    // The JPG is automatically scaled to the size of the signature based on the signature's font scale
    // and number of text lines.
    

}