How to associate existing file type for Mac OS application in XCode 7?

Question

I am making a simple viewer for jpeg pictures in Xcode 7, and trying to associate Jpeg file type with my application. This is a Cocoa application for OS X in Swift that uses storyboards, and is not a document-based application.

Tutorials that I found online suggest going through Info tab, adding a new document type there. Now that's where things start to look different from those in tutorials: in them there is only 3 field to fill out (Name, Types, Icon), but I have many more. I tried to experiment around and here is what I put in fields that I got:

Name: JPEG image
Class: left it blank
Extensions: .jpg, .jpeg, .JPEG, .JPG
Icon: left it blank
Identifier: public.jpeg
Role: Viewer
Mime types: image/jpeg
"Document is distributed as a bundle" is partially checked by default; I just left it as is.
Did not touch additional document type properties either.

As a result I got my application showing in a list in "Open with" when I secondary-click a Jpeg file along with other installed applications, but once I try to open it that way, I get a popup saying The document "picture.jpg" could not be opened. MyApp cannot open files in the "JPEG image" format.

What am I doing wrong?

Really nothing else except the above. The code does not have anything specific to handle the file opened. I just did not get there yet. I guess I am doing something completely wrong? — ZenJ

AlexV AlexV · Accepted Answer · 2016-10-18T03:22:08

The Class field is compulsory, and you have to have corresponding implementation.

Try:

Class: $(PRODUCT_MODULE_NAME).Document

And then add the Document.swift:

import Cocoa

class Document : NSDocument
{

    override init() {
        super.init()
        // Add your subclass-specific initialization here.
    }

    override class func autosavesInPlace() -> Bool {
        return true
    }

    override func makeWindowControllers() {
        // Returns the Storyboard that contains your Document window.
        let storyboard = NSStoryboard(name: "Main", bundle: nil)
        let windowController = storyboard.instantiateController(withIdentifier: "Document Window Controller") as! NSWindowController
        self.addWindowController(windowController)
    }

    override func data(ofType typeName: String) throws -> Data {
        // Insert code here to write your document to data of the specified type. If outError != nil, ensure that you create and set an appropriate error when returning nil.
        // You can also choose to override fileWrapperOfType:error:, writeToURL:ofType:error:, or writeToURL:ofType:forSaveOperation:originalContentsURL:error: instead.
        throw NSError(domain: NSOSStatusErrorDomain, code: unimpErr, userInfo: nil)
    }

    override func read(from data: Data, ofType typeName: String) throws {
        // Insert code here to read your document from the given data of the specified type. If outError != nil, ensure that you create and set an appropriate error when returning false.
        // You can also choose to override readFromFileWrapper:ofType:error: or readFromURL:ofType:error: instead.
        // If you override either of these, you should also override -isEntireFileLoaded to return false if the contents are lazily loaded.
        throw NSError(domain: NSOSStatusErrorDomain, code: unimpErr, userInfo: nil)
    }

}

^ Modify as you need.

Also, you specified the role "Viewer", means you can open it with the space bar, and not the double click (open) - which is the role "Edit" right?

How to associate existing file type for Mac OS application in XCode 7?

1 Answers