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Create Digital Signatures ​

Creating a digital signature involves two steps:

  1. Create a Signature Field

  2. Sign within the Signature Field

By following these two steps, you can either self-sign a document or invite others to sign within the signature field you've created.

Create a Signature Field ​

ComPDFKit offers support for customizing the styles of the signature form field and allows you to customize the appearance of your signature using drawn, image, and typed signatures.

This example shows how to create a signature field：

swift
// Create a signature field.
// 
// Page Index: 0
// Rect: CRect(28, 420, 150, 370)
// Border RGB:{ 0, 0, 0 }  
// Widget Background RGB: { 150, 180, 210 }
// 

if let url = Bundle.main.url(forResource: "filename", withExtension: "pdf") {
    let document = CPDFDocument(url: url)
    if let page = document?.page(at: 0) {
        let widgetAnnotation = CPDFSignatureWidgetAnnotation(document: document)
        
        widgetAnnotation.fieldName = "Signature_\(self.tagString())"
        widgetAnnotation.borderWidth = 2.0
        widgetAnnotation.bounds = CGRect(x: 28, y: 420, width: 150, height: 370)
        widgetAnnotation.modificationDate = Date()
        
        page.addAnnotation(widgetAnnotation)
    }
}
objective-c
// Create a signature field.
// 
// Page Index: 0
// Rect: CRect(28, 420, 150, 370)
// Border RGB:{ 0, 0, 0 }  
// Widget Background RGB: { 150, 180, 210 }
// 

NSURL *url = [NSURL fileURLWithPath:@"file path"];

CPDFDocument *document = [[CPDFDocument alloc] initWithURL:url];
CPDFPage *page = [document pageAtIndex:0];

CPDFSignatureWidgetAnnotation *widgetAnnotation = [[CPDFSignatureWidgetAnnotation alloc] initWithDocument:self.document];

[widgetAnnotation setFieldName:[NSString stringWithFormat:@"%@%@",@"Signature_",[self tagString]]];

widgetAnnotation.borderWidth = 2.0;
widgetAnnotation.bounds = CGRectMake(28, 420, 150, 370);
[widgetAnnotation setModificationDate:[NSDate date]];
[page addAnnotation:widgetAnnotation];

Sign Within the Signature Field ​

To sign within the signature field, you need to do three things:

  • Possess a certificate that conforms to the PKCS12 standard (in PFX or P12 format) and ensure that you know its password. You can create a compliant digital certificate using the built-in methods within the ComPDFKit SDK.

  • Set the appearance of the digital signature.

  • Write the data into the signature field.

This example shows how to sign within the signature field：

swift
//	   Sign in the signature field.
//
// 	   Text: Grantor Name
// 	   Content:
//     Name: Get grantor name from certificate
//     Date: Now (yyyy.mm.dd)
//     Reason: I am the owner of the document
//     DN: Subject
//     IsContentAlginLeft: False
//     IsDrawLogo: True
//     LogoBitmap: logo.png
//     text color RGB: { 0, 0, 0 }
//     Output file name: document.FileName + "_Signed.pdf"
//

let writeDirectoryPath = NSHomeDirectory().appending("/Documents/Signatures")
let documentURL = self.pdfListView?.document.documentURL
let documentName = documentURL?.lastPathComponent.components(separatedBy: ".").first ?? ""
let writeFilePath = writeDirectoryPath + "/" + "\(documentName)_Signed_\(tagString()).pdf"

if FileManager.default.fileExists(atPath: writeFilePath) {
    try? FileManager.default.removeItem(at: URL(fileURLWithPath: writeFilePath))
}

let contents = CPDFSignatureConfig()
signatureConfig.text = nil
signatureConfig.isDrawOnlyContent = true
signatureConfig.image = image

signatureConfig.isContentAlginLeft = false
signatureConfig.isDrawLogo = true
signatureConfig.isDrawKey = true
signatureConfig.logo = UIImage(named: "ImageNameDigitalSignature", in: Bundle(for: self.classForCoder), compatibleWith: nil)

var contents = signatureConfig.contents ?? []

let configItem1 = CPDFSignatureConfigItem()
configItem1.key = "Digitally signed by Apple Distribution"
configItem1.value = NSLocalizedString(self.signatureCertificate?.issuerDict["CN"] as? String ?? "", comment: "")
contents.append(configItem1)

let configItem2 = CPDFSignatureConfigItem()
configItem2.key = "Date"
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
configItem2.value = dateFormatter.string(from: Date())
contents.append(configItem2)

let configItem3 = CPDFSignatureConfigItem()
configItem3?.key = "DN"
let dn = signatureCertificate?.issuerDict["C"]
configItem3?.value = NSLocalizedString(dn, comment: "")
contents3.append(configItem)

let configItem4 = CPDFSignatureConfigItem()
configItem4?.key = VERSION_KEY
configItem4?.value = infoDictionary["CFBundleShortVersionString"] as? String
contents.append(configItem4)

let configItem5 = CPDFSignatureConfigItem()
configItem5?.key = "Location"
configItem5?.value = NSLocalizedString("<your signing location here>", comment: "")
contents.append(configItem5)

let configItem6 = CPDFSignatureConfigItem()
configItem6?.key = "Reason"
configItem6?.value = NSLocalizedString("<your signing reason here>", comment: "")
contents.append(configItem6)

annotation?.signAppearanceConfig(signatureConfig)

let isSuccess = self.pdfListView?.document.writeSignature(to: URL(fileURLWithPath: writeFilePath), withWidget: widget, pkcs12Cert: path, password: password, location: locationStr, reason: reasonStr, permissions: .none) ?? false
objective-c
//	   Sign in the signature field.
//
// 	   Text: Grantor Name
// 	   Content:
//     Name: Get grantor name from certificate
//     Date: Now (yyyy.mm.dd)
//     Reason: I am the owner of the document
//     DN: Subject
//     IsContentAlginLeft: False
//     IsDrawLogo: True
//     LogoBitmap: logo.png
//     text color RGB: { 0, 0, 0 }
//     Output file name: document.FileName + "_Signed.pdf"
//

NSString *homePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
NSString *writeDirectoryPath = [NSString stringWithFormat:@"%@/%@", homePath, @"Signature"];

if (![[NSFileManager defaultManager] fileExistsAtPath:writeDirectoryPath])
[[NSFileManager defaultManager] createDirectoryAtURL:[NSURL fileURLWithPath:writeDirectoryPath] withIntermediateDirectories:YES attributes:nil error:nil];

NSString *writeFilePath = [NSString stringWithFormat:@"%@/%@_Signed_%@.pdf",writeDirectoryPath,self.pdfListView.document.documentURL.lastPathComponent.stringByDeletingPathExtension,[self tagString]];
if([[NSFileManager defaultManager] fileExistsAtPath:writeFilePath]) {
[[NSFileManager defaultManager] removeItemAtPath:writeFilePath error:nil];
}

CPDFSignatureConfig *signatureConfig = [[CPDFSignatureConfig alloc] init];
signatureConfig.image = image;
signatureConfig.isContentAlginLeft = NO;
signatureConfig.isDrawLogo = YES;
signatureConfig.isDrawKey = YES;
signatureConfig.logo = [UIImage imageNamed:@"ImageNameDigitalSignature"];

NSMutableArray *contents = [NSMutableArray arrayWithArray:signatureConfig.contents];

CPDFSignatureConfigItem *configItem1 = [[CPDFSignatureConfigItem alloc]init];
configItem1.key = @"Digitally signed by Apple Distribution";
configItem1.value = NSLocalizedString([signatureCertificate.issuerDict objectForKey:@"CN"], nil);
[contents addObject:configItem1];

CPDFSignatureConfigItem *configItem2 = [[CPDFSignatureConfigItem alloc]init];
configItem2.key = @"Date";
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
configItem2.value = [dateFormatter stringFromDate:[NSDate date]];
[contents addObject:configItem2];

CPDFSignatureConfigItem *configItem3 = [[CPDFSignatureConfigItem alloc]init];
configItem3.key = @"DN";
configItem3.value = NSLocalizedString([signatureCertificate.subjectDict objectForKey:@"C"], nil);
[contents addObject:configItem3];

CPDFSignatureConfigItem *configItem4 = [[CPDFSignatureConfigItem alloc]init];
configItem4.key = @"ComPDFKit Version";
NSDictionary*infoDictionary = [[NSBundle mainBundle] infoDictionary];
NSString *app_Version = [infoDictionary objectForKey:@"CFBundleShortVersionString"];
configItem4.value = app_Version;
[configItem4 addObject:configItem4];

CPDFSignatureConfigItem *configItem5 = [[CPDFSignatureConfigItem alloc]init];
configItem5.key = @"Reason";
configItem5.value = NSLocalizedString(@"I am the owner of the document.", nil);
[contents addObject:configItem5];

CPDFSignatureConfigItem *configItem6 = [[CPDFSignatureConfigItem alloc]init];
configItem6.key = @"Location";
configItem6.value = NSLocalizedString(@"<your signing location here>", nil);
[contents addObject:configItem6];

signatureConfig.contents = contents;
[widgetAnnotation signWithSignatureConfig:signatureConfig];

BOOL isSuccess = [document writeSignatureToURL:[NSURL fileURLWithPath:writeFilePath] withWidget:widgetAnnotation PKCS12Cert:@"Certificate path" password:@"123" location:@"<your signing location here>" reason:@"I am the owner of the document." permissions:CPDFSignaturePermissionsNone];