Integrating e-Signature in pdf file - ios, issue in co-ordinates - ios

Question

Am trying to integrate the signature in a pdf file by fetching the signature from document directory and could place it on the pdf file on fixed position say (50,50). But when trying to integrate the signature by user's tapping position, it is not placed at appropriate position.
I screenshot of the signature added at multiple position of the pdf file is shown below.
Here I tapped at each and every position of the pdf file, but signature is added only at the centre of the pdf file,
CGPoint tapLocation = [gesture locationInView: self.view];
NSLog(#"tapped location is %# \n",NSStringFromCGPoint(tapLocation));
NSInteger x,y;
x=tapLocation.x;
y=tapLocation.y;
CGRect imageRect = CGRectMake(x,568-y, image.size.width, image.size.height);
Adding signature at tapped location is not possible here, but i tried translateCTM and ScaleCTM that also yields the same result. What else to be done, for getting the signature at appropriate tapping position.
UPDATED QUESTION
webView= [[UIWebView alloc] initWithFrame:CGRectMake(0, 60, 320, 568)];
- (void) singleTap:(UITapGestureRecognizer*)gesture
{
// handle event
NSLog(#"single tap is handled");
CGPoint tapLocation = [gesture locationInView:webView];
NSLog(#"tapped location is %# \n",NSStringFromCGPoint(tapLocation));
NSInteger x,y;
x=tapLocation.x;
y=tapLocation.y;
NSLog(#"location:x %d\n",x);
NSLog(#"location:y %d\n",y);
CGPoint pointInView1 = [webView convertPoint:tapLocation toView:self.window];//change of +80 in y
NSLog(#"pointinview is %# \n",NSStringFromCGPoint(pointInView1));
xy = pointInView1.x;
yz = pointInView1.y;
if (entered==1)
{
// CFStringRef path;
CFURLRef url;
url = (CFURLRef)CFBridgingRetain([NSURL fileURLWithPath:documentDirectoryPath]);
CGPDFDocumentRef myDocument;
myDocument = CGPDFDocumentCreateWithURL((CFURLRef)url);
// Create PDF context
CGContextRef pdfContext = CGPDFContextCreateWithURL(url, NULL, NULL);
int totalPages = (int)CGPDFDocumentGetNumberOfPages(myDocument);
NSLog(#"no. of pages in pdf is %d \n",totalPages);
//alter each page of a pdf
for (int currentPage = 1; currentPage <= totalPages; currentPage++)
{
CGPDFContextBeginPage(pdfContext, NULL);
UIGraphicsPushContext(pdfContext);
CGContextDrawPDFPage(UIGraphicsGetCurrentContext(), CGPDFDocumentGetPage(myDocument, currentPage)); //"page" is current pdf page to be signed
if (page == currentPage)
{
NSString *filePath = [[paths objectAtIndex:0] stringByAppendingPathComponent:#"Image.png"];// "image.png" is the saved user's signature in document directory
image = [[UIImage alloc] initWithContentsOfFile:filePath];
// Translate the origin of the coordinate system at the
// bottom left corner of the page rectangle.
// CGContextTranslateCTM(pdfContext, 0,1);
// Reverse the Y axis to grow from bottom to top.
// CGContextScaleCTM(pdfContext, 1, 1);
CGRect imageRect = CGRectMake(x,568-y, image.size.width, image.size.height);
CGContextDrawImage(UIGraphicsGetCurrentContext(), imageRect, image.CGImage);
}
// Clean up
UIGraphicsPopContext();
CGPDFContextEndPage(pdfContext);
}
CGPDFContextClose(pdfContext);
// _sign_label.text = #"";
}
NSURLRequest *request = [NSURLRequest requestWithURL:targetURL];
[webView loadRequest:request];
[self.view addSubview:webView];
}