> For the complete documentation index, see [llms.txt](https://docs.apryse.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.apryse.com/ios/get-started/samples/sdftest.md).

# SDF

Sample Obj-C code to edit an existing PDF document at the object level by using the Apryse SDK Cos/SDF low-level API.

Sample Obj-C code for editing an existing PDF document at the object level by using the Apryse SDK Cos/SDF low-level API. Learn more about our [iOS SDK](/ios/guides.md) and [PDF Editing & Manipulation Library](/core/page-manipulation/manipulation.md).

{% tabs %}
{% tab title="Obj-C" %}
{% code lineNumbers="true" %}

```objc
//---------------------------------------------------------------------------------------
// Copyright (c) 2001-2024 by Apryse Software Inc. All Rights Reserved.
// Consult legal.txt regarding legal and license information.
//---------------------------------------------------------------------------------------

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

// This sample illustrates how to use basic SDF API (also known as Cos) to edit an 
// existing document.

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

        @try
        {
            NSLog(@"Opening the test file...");

            // Here we create a SDF/Cos document directly from PDF file. In case you have 
            // PDFDoc you can always access SDF/Cos document using PDFDoc.GetSDFDoc() method.
            PTSDFDoc *doc = [[PTSDFDoc alloc] initWithFilepath: @"../../TestFiles/fish.pdf"];
            [doc InitSecurityHandler];

            NSLog(@"Modifying info dictionary, adding custom properties, embedding a stream...");
            PTObj * trailer = [doc GetTrailer]; // Get the trailer

            // Now we will change PDF document information properties using SDF API

            // Get the Info dictionary. 
            PTDictIterator *itr = [trailer Find: @"Info"];
            PTObj * info = [[PTObj alloc] init];
            if ([itr HasNext]) 
            {
                info = [itr Value];
                // Modify 'Producer' entry.
                [info PutString: @"Producer" value: @"PDFTron PDFNet"];

                // Read title entry (if it is present)
                itr = [info Find: @"Author"]; 
                if ([itr HasNext]) 
                {
                    NSString *oldstr = [[itr Value] GetAsPDFText];
                    [info PutText: @"Author" value: [oldstr stringByAppendingString: @"- Modified"]];
                }
                else 
                {
                    [info PutString: @"Author" value: @"Me, myself, and I"];
                }
            }
            else 
            {
                // Info dict is missing. 
                info = [trailer PutDict: @"Info"];
                [info PutString: @"Producer" value: @"PDFTron PDFNet"];
                [info PutString: @"Title" value: @"My document"];
            }

            // Create a custom inline dictionary within Info dictionary
            PTObj * custom_dict = [info PutDict: @"My Direct Dict"];
            [custom_dict PutNumber: @"My Number" value: 100]; // Add some key/value pairs
            [custom_dict PutArray: @"My Array"];

            // Create a custom indirect array within Info dictionary
            PTObj * custom_array = [doc CreateIndirectArray];
            [info Put: @"My Indirect Array" obj: custom_array]; // Add some entries
            
            // Create indirect link to root
            [custom_array PushBack: [[trailer Get: @"Root"] Value]];

            // Embed a custom stream (file mystream.txt).
            PTMappedFile *embed_file = [[PTMappedFile alloc] initWithFilename: @"../../TestFiles/my_stream.txt"];
            PTFilterReader *mystm = [[PTFilterReader alloc] initWithFilter: embed_file];
            [custom_array PushBack: [doc CreateIndirectStream: mystm]];

            // Save the changes.
            NSLog(@"Saving modified test file...");
            [doc SaveSDFDocToFile: @"../../TestFiles/Output/sdftest_out.pdf" flags:0 header: @"%PDF-1.4"];

            NSLog(@"Test completed.");
        }
        @catch (NSException *e)
        {
            NSLog(@"%@", e.reason);
            ret = 1;
        }
        [PTPDFNet Terminate: 0];
        return ret;
    }
}
```

{% endcode %}
{% endtab %}

{% tab title="Swift" %}
{% code lineNumbers="true" %}

```swift
//---------------------------------------------------------------------------------------
// Copyright (c) 2001-2019 by PDFTron Systems Inc. All Rights Reserved.
// Consult legal.txt regarding legal and license information.
//---------------------------------------------------------------------------------------

import PDFNet
import Foundation

// This sample illustrates how to use basic SDF API (also known as Cos) to edit an
// existing document.

func runSDFTest() -> Int {
    return autoreleasepool {
        var ret: Int = 0
        

        do {
            try PTPDFNet.catchException {
                print("Opening the test file...")
                
                // Here we create a SDF/Cos document directly from PDF file. In case you have
                // PDFDoc you can always access SDF/Cos document using PDFDoc.GetSDFDoc() method.
                let doc: PTSDFDoc = PTSDFDoc(filepath: Bundle.main.path(forResource: "fish", ofType: "pdf"))
                doc.initSecurityHandler()
                
                print("Modifying info dictionary, adding custom properties, embedding a stream...")
                let trailer: PTObj = doc.getTrailer()  // Get the trailer

                // Now we will change PDF document information properties using SDF API
                
                // Get the Info dictionary.
                var itr: PTDictIterator = trailer.find("Info")
                var info: PTObj = PTObj()
                if itr.hasNext() {
                    info = itr.value()
                    // Modify 'Producer' entry.
                    info.put("Producer", value: "PDFTron PDFNet")
                
                    // Read title entry (if it is present)
                    itr = info.find("Author")
                    if itr.hasNext() {
                        let oldstr: String = itr.value().getAsPDFText()
                        info.putText("Author", value: oldstr + "- Modified")
                    }
                    else {
                        info.put("Author", value: "Me, myself, and I")
                    }
                }
                else {
                    // Info dict is missing.
                    info = (trailer.putDict("Info"))!
                    info.put("Producer", value: "PDFTron PDFNet")
                    info.put("Title", value: "My document")
                }

                // Create a custom inline dictionary within Info dictionary
                let custom_dict: PTObj = info.putDict("My Direct Dict")
                custom_dict.putNumber("My Number", value: 100)  // Add some key/value pairs
                custom_dict.putArray("My Array")
                
                // Create a custom indirect array within Info dictionary
                let custom_array: PTObj = doc.createIndirectArray()
                info.put("My Indirect Array", obj: custom_array)    // Add some entries
                
                // Create indirect link to root
                custom_array.pushBack(trailer.get("Root").value())
                
                // Embed a custom stream (file mystream.txt).
                let embed_file = PTMappedFile(filename: Bundle.main.path(forResource: "my_stream", ofType: "txt"))
                let mystm = PTFilterReader(filter: embed_file)
                custom_array.pushBack(doc.createIndirectStream(mystm))
                
                // Save the changes.
                print("Saving modified test file...")
                doc.save(toFile: URL(fileURLWithPath: NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]).appendingPathComponent("sdftest_out.pdf").path, flags: 0, header: "%PDF-1.4")
                
                print("Test completed.")
            }
        } catch let e as NSError {
            print("\(e)")
            ret = 1
        }
        return ret
    }
}
```

{% endcode %}
{% endtab %}
{% endtabs %}


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