Swift Requires Chilkat v11.7.0+

Remove PDF Objects Nothing Refers To

See more PDF Optimization Examples

Demonstrates removeUnreferenced. When a page, an image or a whole section is replaced in an editor, the objects it used often stay in the file with nothing pointing at them any more. They are not old revisions -- they are in the current revision, simply unreachable -- so only a reachability walk from the document catalog finds them. In a publication assembled over several editing passes this is frequently the largest single saving. Swift

func chilkatTest() {
    var success: Bool = false

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

    //  The PDF used in this example is available at watersense_accomplishments.pdf

    let pdf = CkoPdf()!
    success = pdf.loadFile(filePath: "qa_data/pdf/watersense_accomplishments.pdf")
    if success == false {
        print("\(pdf.lastErrorText!)")
        return
    }

    let json = CkoJsonObject()!
    let jsonOut = CkoJsonObject()!
    success = pdf.optimize(op: "audit", jsonIn: json, jsonOut: jsonOut)
    if success == false {
        print("\(pdf.lastErrorText!)")
        return
    }

    print("fileSize: \(jsonOut.int(of: "fileSize").intValue)")
    print("removeUnreferenced would save: \(jsonOut.int(of: "estimatedSavings.removeUnreferenced").intValue)")

    //  Optimize with the defaults and see how many objects were actually dropped.
    success = pdf.optimize(op: "optimize", jsonIn: json, jsonOut: jsonOut)
    if success == false {
        print("\(pdf.lastErrorText!)")
        return
    }

    success = pdf.writeFile(path: "qa_output/watersense_optimized.pdf")
    if success == false {
        print("\(pdf.lastErrorText!)")
        return
    }

    print("objects removed: \(jsonOut.int(of: "actions.removeUnreferenced.count").intValue)")
    print("bytes saved:     \(jsonOut.int(of: "actions.removeUnreferenced.bytesSaved").intValue)")

    //  Nothing a page needs is ever removed: the walk starts at the document catalog and follows every
    //  reference, including the ones in annotations, the structure tree, named destinations and the
    //  optional-content configuration.
    print("pages after: \(pdf.numPages.intValue)")

}