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Obj-C PDF editor (programmatic)

Sample Obj-C code for using PDFTron SDK to programmatically edit an existing PDF document's page display list and the graphics state attributes on existing elements. In particular, this sample strips all images from the page and changes the text color to blue. You can also build a GUI with interactive PDF editor widgets. Some of PDFTron SDK's other functions for programmatically editing PDFs include the Cos/SDF low-level API, page manipulation, and more. Learn more about our PDF Editing & Manipulation Library.

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//---------------------------------------------------------------------------------------
// Copyright (c) 2001-2012 by PDFTron Systems Inc. All Rights Reserved.
// Consult legal.txt regarding legal and license information.
//---------------------------------------------------------------------------------------

#import <OBJC/PDFNetOBJC.h>
#import <Foundation/Foundation.h>

//---------------------------------------------------------------------------------------
// The sample code shows how to edit the page display list and how to modify graphics state 
// attributes on existing Elements. In particular the sample program strips all images from 
// the page, changes path fill color to red, and changes text color to blue. 
//---------------------------------------------------------------------------------------

static void ProcessElementEditTestElements(PTElementReader *reader, PTElementWriter *writer, NSMutableSet *visited)
{
	PTElement *element;	
	while ((element = [reader Next])) 	// Read page contents
	{
		switch ([element GetType])
		{		
		case e_ptimage: 
		case e_ptinline_image: 
			// remove all images by skipping them			
			break;
		case e_ptpath:
			{
				// Set all paths to red color.
				PTGState *gs = [element GetGState];
				[gs SetFillColorSpace: [PTColorSpace CreateDeviceRGB]];
				PTColorPt *cp = [[PTColorPt alloc] initWithX: 1 y: 0 z: 0 w: 0];
				[gs SetFillColorWithColorPt: cp];
				[writer WriteElement: element];
				break;
			}
		case e_pttext_obj:
			{
				// Set all text to blue color.
				PTGState *gs = [element GetGState];
				[gs SetFillColorSpace: [PTColorSpace CreateDeviceRGB]];
				PTColorPt *cp = [[PTColorPt alloc] initWithX: 0 y: 0 z: 1 w: 0];
				[gs SetFillColorWithColorPt: cp];
				[writer WriteElement: element];
				break;
			}
		case e_ptform:
			{
				[writer WriteElement: element]; // write Form XObject reference to current stream

				PTObj *form_obj = [element GetXObject];

				if (![visited containsObject:@([form_obj GetObjNum])]) // if this XObject has not been processed
				{
					// recursively process the Form XObject
					[visited addObject:@([form_obj GetObjNum])];
					PTElementWriter *new_writer = [[PTElementWriter alloc] init];
					[reader FormBegin];
					[new_writer WriterBeginWithSDFObj:form_obj compress:YES resources: NULL];
					
					[reader ClearChangeList];
					[new_writer SetDefaultGState: reader];
					
					ProcessElementEditTestElements(reader, new_writer, visited);
					[reader End];
					[new_writer End];
				}

				break; 
			}
		default:
                [writer WriteElement: element];
		}
	}
}

int main(int argc, char *argv[])
{
    @autoreleasepool {
	
        int ret = 0;
        [PTPDFNet Initialize: 0];

        @try 
        {
            NSLog(@"Opening the input file...");
            PTPDFDoc *doc = [[PTPDFDoc alloc] initWithFilepath: @"../../TestFiles/newsletter.pdf"];
            [doc InitSecurityHandler];

            PTElementWriter *writer = [[PTElementWriter alloc] init];
            PTElementReader *reader = [[PTElementReader alloc] init];
            NSMutableSet *visited = [[NSMutableSet alloc] init];

            PTPageIterator *itr = [doc GetPageIterator: 1];
            while ([itr HasNext])
            {
                PTPage *page = [itr Current];
                [visited addObject:@([[page GetSDFObj] GetObjNum])];

                [reader ReaderBeginWithPage: page ocg_context: 0];
                [writer WriterBeginWithPage: page placement: e_ptreplacement page_coord_sys: NO compress: YES resources: [page GetResourceDict] ];
                
                ProcessElementEditTestElements(reader, writer, visited);

                [writer End];
                [reader End];
                
                [itr Next];
            }

            // Save modified document
        [doc SaveToFile: @"../../TestFiles/Output/newsletter_edited.pdf" flags: e_ptremove_unused];		
        NSLog(@"Done. Result saved in newsletter_edited.pdf...");
        }
        @catch(NSException *e)
        {
            NSLog(@"Caught PDFNet exception: %@", e.reason);
            ret = 1;
        }
        
        return ret;
        
    }
    
}
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