Function in Swift to Append a Pdf file to another Pdf

Question

I created two different pdf files in two different views using following code:

private func toPDF(views: [UIView]) -> NSData? {

    if views.isEmpty {return nil}

    let pdfData = NSMutableData()
    UIGraphicsBeginPDFContextToData(pdfData, CGRect(x: 0, y: 0, width: 1024, height: 1448), nil)
    let context = UIGraphicsGetCurrentContext()

    for view in views {
        UIGraphicsBeginPDFPage()
        view.layer.renderInContext(context!)
    }

    UIGraphicsEndPDFContext()

    return pdfData
}

In the final view I call both files using:

let firstPDF = NSUserDefaults.standardUserDefaults().dataForKey("PDFone")
let secondPDF = NSUserDefaults.standardUserDefaults().dataForKey("PDFtwo")

My question is: Can anyone suggest a function which append the second file to the first one? (Both are in NSData Format)

Answer 1

Swift 4:

func merge(pdfs:Data...) -> Data
{
    let out = NSMutableData()
    UIGraphicsBeginPDFContextToData(out, .zero, nil)

    guard let context = UIGraphicsGetCurrentContext() else {
        return out as Data
    }

    for pdf in pdfs {
        guard let dataProvider = CGDataProvider(data: pdf as CFData), let document = CGPDFDocument(dataProvider) else { continue }

        for pageNumber in 1...document.numberOfPages {
            guard let page = document.page(at: pageNumber) else { continue }
            var mediaBox = page.getBoxRect(.mediaBox)
            context.beginPage(mediaBox: &mediaBox)
            context.drawPDFPage(page)
            context.endPage()
        }
    }

    context.closePDF()
    UIGraphicsEndPDFContext()

    return out as Data
}

Answer 2

This can be done quite easily with PDFKit and its PDFDocument.

I'm using this extension:

    import PDFKit
    
    extension PDFDocument {
    
        func addPages(from document: PDFDocument) {
            let pageCountAddition = document.pageCount
    
            for pageIndex in 0..<pageCountAddition {
                guard let addPage = document.page(at: pageIndex) else {
                    break
                }
    
                self.insert(addPage, at: self.pageCount) // unfortunately this is very very confusing. The index is the page *after* the insertion. Every normal programmer would assume insert at self.pageCount-1
            }
        }
    
    }