How to generate grid in PDF using Cocoa? - objective-c

Question

I'm a beginner to Cocoa and Objective-C.
I want to make a Cocoa application that will generate a grid of boxes (used for practicing Chinese calligraphy) to export as a PDF, similar to this online generator: http://incompetech.com/graphpaper/chinesequarter/.
How should I generate the grid? I've tried to use Quartz with a CustomView, but didn't manage to get very far. Also, once the grid is drawn in the CustomView, what is the method for "printing" that to a PDF?
Thanks for the help.

Answer 1

How should I generate the grid?
Implement a custom view that draws it.
I've tried to use Quartz with a CustomView, …
That's one way; AppKit drawing is the other. Most parts of them are very similar, though; AppKit is directly based on PostScript, while Quartz is indirectly based on PostScript.
… but didn't manage to get very far.
You should ask a more specific question about your problem.
Also, once the grid is drawn in the CustomView, what is the method for "printing" that to a PDF?
Send it a dataWithPDFInsideRect: message, passing its bounds.
Note that there is no “once the grid is drawn in the CustomView”. Though there may be some internal caching, conceptually, a view does not draw once and hold onto it; it draws when needed, every time it's needed, into where it's needed. When the window needs to be redrawn, Cocoa will tell any views that are in the dirty area to (re)draw, and they will draw ultimately to the screen. When you ask for PDF data, that will also tell the view to draw, and it will draw into a context that records PDF data. This allows the view both to be lazy (draw only when needed) and to draw differently in different contexts (e.g., when printing).

Answer 2

Oops, you were asking about Cocoa and this is Cocoa Touch, but I'll leave it here as it may be some use (at least to others who find this later).
You can draw things in the view and then put what's there into a pdf.
This code will take what's drawn in a UIView (called sheetView here), put it into a pdf, then put that as an attachment in an email (so you can see it for now). You'll need to reference the protocol MFMailComposeViewControllerDelegate in your header.
if ([MFMailComposeViewController canSendMail]) {
//set up PDF rendering context
NSMutableData *pdfData = [NSMutableData data];
UIGraphicsBeginPDFContextToData(pdfData, sheetView.bounds, nil);
UIGraphicsBeginPDFPage();
//tell our view to draw (would normally use setNeedsDisplay, but need drawn now).
[sheetView drawRect:sheetView.bounds];
//remove PDF rendering context
UIGraphicsEndPDFContext();
//send PDF data in mail message as an attachment
MFMailComposeViewController *mailComposer = [[[MFMailComposeViewController alloc] init] autorelease];
mailComposer.mailComposeDelegate = self;If
[mailComposer addAttachmentData:pdfData mimeType:#"application/pdf" fileName:#"SheetView.pdf"];
[self presentModalViewController:mailComposer animated:YES];
}
else {
if (WARNINGS) NSLog(#"Device is unable to send email in its current state.");
}
You'll also need this method...
#pragma mark -
#pragma mark MFMailComposeViewControllerDelegate protocol method
//also need to implement the following method, so that the email composer can let
//us know that the user has clicked either Send or Cancel in the window.
//It's our duty to end the modal session here.
-(void)mailComposeController:(MFMailComposeViewController *)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError *)error {
[self dismissModalViewControllerAnimated:YES];
}