Objective-C Requires Chilkat v11.7.0+

Extract Text from a Two-Column PDF

See more PDF Text Extraction Examples

Demonstrates how multi-column pages are read. By default the columns are detected and each column is read top to bottom before the next ("columns": "auto"); "columns": "none" reads the full page width line by line, which interleaves the columns. The quality report tells how many columns were found. Objective-C

#import <CkoPdf.h>
#import <CkoJsonObject.h>

BOOL success = NO;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  The two-column PDF used in this example is available at two_column_article.pdf

CkoPdf *pdf = [[CkoPdf alloc] init];
success = [pdf LoadFile: @"qa_data/pdf/two_column_article.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

CkoJsonObject *json = [[CkoJsonObject alloc] init];
CkoJsonObject *jsonOut = [[CkoJsonObject alloc] init];

//  With the default options the columns are detected, and the text of the left column
//  comes before the text of the right column.
success = [pdf ExtractText: @"text" jsonIn: json jsonOut: jsonOut];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

NSLog(@"%@%d",@"Columns detected: ",[[jsonOut IntOf: @"quality.pages[0].columns"] intValue]);
NSLog(@"%@%@",@"Reading order: ",[jsonOut StringOf: @"quality.pages[0].readingOrderSource"]);
NSLog(@"%@",[jsonOut StringOf: @"text"]);

//  "none" switches column detection off: the page is read across its full width, line by line,
//  so each output line holds a line of the left column followed by a line of the right column.
//  This is rarely wanted, but it shows what the detection does.
[json UpdateString: @"columns" value: @"none"];
[json UpdateString: @"layout" value: @"lines"];
success = [pdf ExtractText: @"text" jsonIn: json jsonOut: jsonOut];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

NSLog(@"%@",@"---- columns: none ----");
NSLog(@"%@",[jsonOut StringOf: @"text"]);

//  Sample output (abbreviated):

//  Columns detected: 2
//  Reading order: visual
//  The Harbor Lighthouse, Season Two
//  
//  The harbor lighthouse was built in 1874 to mark the entrance to the inner channel. It operated continuously until 1968, ...
//  
//  The restoration society took ownership in 2021 with three goals: ...
//  ...
//  The lantern room frame was stripped, primed and repainted in the original dark green. ...
//  ...
//  ---- columns: none ----
//  The Harbor Lighthouse, Season Two
//  The harbor lighthouse was built in 1874 to The lantern room frame was stripped, primed
//  mark the entrance to the inner channel. It and repainted in the original dark green. New
//  ...