Swift

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.

Swift

func chilkatTest() {
    var success: Bool = false

    //  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
    success = pdf.loadFile(filePath: "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(jsonPath: "signingCertificateV2", value: 1)
    json.updateInt(jsonPath: "signingTime", value: 1)

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

    //  Use a font scale of 10.0
    json.updateString(jsonPath: "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(jsonPath: "appearance.text[0]", value: "Digitally signed by: cert_cn")
    json.updateString(jsonPath: "appearance.text[1]", value: "current_dt")
    json.updateString(jsonPath: "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(path: "qa_data/jpg/university.jpg")
    if success == false {
        print("Failed to load the JPG image.")
        return
    }

    success = pdf.setSignatureJpeg(jpgData: 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(jsonPath: "appearance.image", value: "custom-jpg")
    json.updateString(jsonPath: "appearance.imagePlacement", value: "center")
    json.updateString(jsonPath: "appearance.imageOpacity", value: "30")

    //  Load the signing certificate. (Use your own certificate.)
    let cert = CkoCert()!
    success = cert.loadPfxFile(path: "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: cert)
    if success == false {
        print("\(pdf.lastErrorText!)")
        return
    }

    success = pdf.sign(jsonOptions: 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.
    //  

}