I have solved by creating the new PDF and drawing the pdf data and signature on it. Please refer following code:
// For adding the Siganture we need to wite the content on new PDF
-(void) addSignature:(UIImage *) imgSignature onPDFData:(NSData *)pdfData {
NSMutableData* outputPDFData = [[NSMutableData alloc] init];
CGDataConsumerRef dataConsumer = CGDataConsumerCreateWithCFData((CFMutableDataRef)outputPDFData);
CFMutableDictionaryRef attrDictionary = NULL;
attrDictionary = CFDictionaryCreateMutable(NULL, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
CFDictionarySetValue(attrDictionary, kCGPDFContextTitle, CFSTR("My Doc"));
CGContextRef pdfContext = CGPDFContextCreate(dataConsumer, NULL, attrDictionary);
CFRelease(dataConsumer);
CFRelease(attrDictionary);
CGRect pageRect;
// Draw the old "pdfData" on pdfContext
CFDataRef myPDFData = (__bridge CFDataRef) pdfData;
CGDataProviderRef provider = CGDataProviderCreateWithCFData(myPDFData);
CGPDFDocumentRef pdf = CGPDFDocumentCreateWithProvider(provider);
CGDataProviderRelease(provider);
CGPDFPageRef page = CGPDFDocumentGetPage(pdf, 1);
pageRect = CGPDFPageGetBoxRect(page, kCGPDFMediaBox);
CGContextBeginPage(pdfContext, &pageRect);
CGContextDrawPDFPage(pdfContext, page);
// Draw the signature on pdfContext
pageRect = CGRectMake(0, 0,imgSignature.size.width , imgSignature.size.height);
CGImageRef pageImage = [imgSignature CGImage];
CGContextDrawImage(pdfContext, pageRect, pageImage);
// release the allocated memory
CGPDFContextEndPage(pdfContext);
CGPDFContextClose(pdfContext);
CGContextRelease(pdfContext);
// write new PDFData in "outPutPDF.pdf" file in document directory
NSString *docsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *pdfFilePath =[NSString stringWithFormat:@"%@/outPutPDF.pdf",docsDirectory];
[outputPDFData writeToFile:pdfFilePath atomically:YES];
}