drag and drop - iOS 11 dropInteraction performDrop for files

Question

How can I use dropInteraction(_ interaction: UIDropInteraction, performDrop session: UIDropSession) to accept other type of files than images? Say for instnce that I drag a PDF or MP3 from the files app. How can I accept this file and get the data?

I thought I could use NSURL.self, but that only seems to work for URL's dragged from Safari och a textview.

Answer 1

An example for PDF (com.adobe.pdf UTI) implementing NSItemProviderReading could be something like this:

class PDFDocument: NSObject, NSItemProviderReading {
    let data: Data?

    required init(pdfData: Data, typeIdentifier: String) {
        data = pdfData
    }

    static var readableTypeIdentifiersForItemProvider: [String] {
        return [kUTTypePDF as String]
    }

    static func object(withItemProviderData data: Data, typeIdentifier: String) throws -> Self {
        return self.init(pdfData: data, typeIdentifier: typeIdentifier)
    }
}

Then in your delegate you need to handle this PDFDocument:

extension YourClass: UIDropInteractionDelegate {
    func dropInteraction(_ interaction: UIDropInteraction, canHandle session: UIDropSession) -> Bool {
        return session.canLoadObjects(ofClass: PDFDocument.self))
    }

    .
    .
    .

    func dropInteraction(_ interaction: UIDropInteraction, performDrop session: UIDropSession) {
        session.loadObjects(ofClass: PDFDocument.self) { [unowned self] pdfItems in
            if let pdfs = pdfItems as? [PDFDocument], let pdf = pdfs.first {
                // Whatever you want to do with the pdf
            }
        }
    }
}