Objective-C

PDF Signature Appearance Text Substitution Keywords

See more PDF Signatures Examples

This example demonstrates the text substitution keywords that can be used in the PDF signature's appearance text.

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

Objective-C

#import <CkoPdf.h>
#import <CkoJsonObject.h>
#import <CkoBinData.h>
#import <CkoCert.h>

BOOL success = NO;

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

CkoPdf *pdf = [[CkoPdf alloc] init];

// Load a PDF to be signed.
success = [pdf LoadFile: @"qa_data/pdf/empty.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

// Options for signing are specified in JSON.
CkoJsonObject *json = [[CkoJsonObject alloc] init];

// In most cases, the signingCertificateV2 and signingTime attributes are required.
[json UpdateInt: @"signingCertificateV2" value: [NSNumber numberWithInt: 1]];
[json UpdateInt: @"signingTime" value: [NSNumber numberWithInt: 1]];

// Put the signature on page 1, top left
[json UpdateInt: @"page" value: [NSNumber numberWithInt: 1]];
[json UpdateString: @"appearance.y" value: @"top"];
[json UpdateString: @"appearance.x" value: @"left"];

// Use a font scale of 7.0
[json UpdateString: @"appearance.fontScale" value: @"7.0"];

// The appearance of the PDF signature can contain any number of text lines.
// Chilkat has defined a number of special keywords that can be used in any text line.
// Each keyword is replaced with the actual value.
// For example, "cert_cn" is replaced with the certificate subject's common name (CN).

// Here we are creating a signature with many lines of text, to demonstrate each
// keyword.
[json UpdateString: @"appearance.text[0]" value: @"Date/time in PDF format: current_dt"];
[json UpdateString: @"appearance.text[1]" value: @"Current Local date/time: current_datetime"];
[json UpdateString: @"appearance.text[2]" value: @"GMT Timestamp: current_timestamp_gmt"];
[json UpdateString: @"appearance.text[3]" value: @"Local Timestamp: current_timestamp_local"];
[json UpdateString: @"appearance.text[4]" value: @"GMT RFC822 date/time: current_rfc822_dt_gmt"];
[json UpdateString: @"appearance.text[5]" value: @"Local RFC822 date/time: current_rfc822_dt_local"];
[json UpdateString: @"appearance.text[6]" value: @"Cert DN (Distinguished Name): cert_dn"];
[json UpdateString: @"appearance.text[7]" value: @"Cert Common Name: cert_cn"];
[json UpdateString: @"appearance.text[8]" value: @"Cert Organizational ID (2.5.4.97): cert_org_id"];
[json UpdateString: @"appearance.text[9]" value: @"Cert Email: cert_email"];
[json UpdateString: @"appearance.text[10]" value: @"Cert Organization: cert_organization"];
[json UpdateString: @"appearance.text[11]" value: @"Cert Organziational Unit: cert_ou"];
[json UpdateString: @"appearance.text[12]" value: @"Cert State: cert_state"];
[json UpdateString: @"appearance.text[13]" value: @"Cert Country: cert_country"];
[json UpdateString: @"appearance.text[14]" value: @"Cert Locality: cert_locality"];
[json UpdateString: @"appearance.text[15]" value: @"Cert Serial Number (hex): cert_serial_hex"];
[json UpdateString: @"appearance.text[16]" value: @"Cert Serial Number (decimal): cert_serial_dec"];
[json UpdateString: @"appearance.text[17]" value: @"Cert Thumbprint: cert_thumbprint"];
[json UpdateString: @"appearance.text[18]" value: @"Cert Issuer Common Name: cert_issuer_cn"];

CkoBinData *jpgData = [[CkoBinData alloc] init];
success = [jpgData LoadFile: @"qa_data/jpg/seal1.jpg"];
if (success == NO) {
    NSLog(@"%@",@"Failed to load the JPG image.");
    return;
}

success = [pdf SetSignatureJpeg: jpgData];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

// Specify that we want to display the JPG image in the center with 33% opacity.
[json UpdateString: @"appearance.image" value: @"custom-jpg"];
[json UpdateString: @"appearance.imagePlacement" value: @"center"];
[json UpdateString: @"appearance.imageOpacity" value: @"33"];

// Load the signing certificate. (Use your own certificate.)
CkoCert *cert = [[CkoCert alloc] init];
success = [cert LoadPfxFile: @"qa_data/pfx/myPdfSigningCert.pfx" password: @"pfx_password"];
if (success == NO) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

// Tell the pdf object to use the certificate for signing.
success = [pdf SetSigningCert: cert];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

success = [pdf SignPdf: json outFilePath: @"qa_output/hello_signed.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

NSLog(@"%@",@"The PDF has been successfully cryptographically signed.");

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

// (image:https://example-code.com/images/pdf_signature_text_replacements.jpg/endImage)