iOS 11 Extracting filename when doing Drag and Drop PDF from Dropbox

Question

I have implemented iOS 11 Drag and Drop to allow PDF files to be dragged into my App from Files on iPad.

I have a DragDropFile class as follows:

import Foundation
import MobileCoreServices


//Drag and drop PDF files

class DragDropFile : NSObject, NSItemProviderReading {
    let fileData:Data?

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

    static var readableTypeIdentifiersForItemProvider: [String] {
        var documentTypeArray: [String] = []

        documentTypeArray = [kUTTypePDF as String]
        return documentTypeArray

    }

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

Then canHandle specifies this class:

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

This works fine for dropping PDF files dragged from DropBox!

However, my App also needs access to the original PDF file name.

I would have expected to be able to also drop the URL as follows:

func dropInteraction(_ interaction: UIDropInteraction, canHandle session: UIDropSession) -> Bool {
        return session.canLoadObjects(ofClass: NSURL.self) && session.canLoadObjects(ofClass: DragDropFile.self) 
    }

Unfortunately, this does not work with DropBox as there appears to be no associated URL.

Does anyone know how to drag and drop and access the file name?

Thanks!

Did you ever get anywhere with this? I'm having trouble with receiving files dropped from Dropbox. Calling item.itemProvider.loadDataRepresentation(forTypeIdentifier: kUTTypePDF as String, completionHandler: completionHandler) results in the error: "The file “PDF document.pdf” couldn’t be opened because there is no such file." — colincameron
I assume you get the content of a PDF and not the filename? But still it is interesting to know the file name of the file dropped on our app? Suggestion of Wei WANG does it. — Jan Bergström

Wei WANG Wei WANG · Accepted Answer · 2018-12-21T04:08:14

I had the similar problem of getting the original filename, and after one day's digging I've come to the following solution (dragging files from Apple's Files app):

func tableView(_ tableView: UITableView, performDropWith coordinator: UITableViewDropCoordinator) {
    let filenameWithoutExtension = coordination.session.items.first?.itemProvider.suggestedName
}

I've used TableView in my case so in your case it should be something like:

func dropInteraction(_ interaction: UIDropInteraction, performDrop session: UIDropSession) {
    let filenameWithoutExtension = session.items.first?.itemProvider.suggestedName
}

See here for reference (though very little information).

And note the suggestedName you retrieve from the above API is without the extension name. However it should not be a big deal since you've got the UTI so you know what exactly extension name should be... In my case I get it like:

class DragDropFile : NSObject, NSItemProviderReading {
    let fileData: Data?
    let extensionName: String?

    required init(data:Data, typeIdentifier:String) {
        fileData = data
        if typeIdentifier == (kUTTypePDF as String) {
            extensionName = "pdf"
        } else if typeIdentifier == (kUTTypePNG as String) {
            extensionName = "png"
        } else {
            //.,..
        }
    }
}

==== Updated 2/1/2019 ===

I ended up using UTTypeCopyPreferredTagWithClass to get the extension name from UTI:

class DragDropFile : NSObject, NSItemProviderReading {
    let fileData: Data?
    let extensionName: String?

    required init(data:Data, typeIdentifier:String) {
        fileData = data
        let cfExtensionName = UTTypeCopyPreferredTagWithClass(typeIdentifier as CFString, kUTTagClassFilenameExtension)
        self.extensionName = cfExtensionName?.takeRetainedValue() as String?
    }

    static var readableTypeIdentifiersForItemProvider: [String] {
        var documentTypeArray: [String] = []

        for ext in ["doc", "docx", "other_extensions..."] {
            let UTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, ext as CFString, nil)
            if let documentType = UTI?.takeRetainedValue() as String? {
                documentTypeArray.append(documentType)
            }
        }

        return documentTypeArray
    }

}

iOS 11 Extracting filename when doing Drag and Drop PDF from Dropbox

1 Answers