Drag messages from Mail onto Dock using Swift

Question

I am trying to get my application to accept a mail message that was dropped onto my application\'s dock icon directly from Mail.

I have followed this link Dropping File

Answer 1

You can extract the mail item's URL by registering your app as a service by adding the following to your app's info.plist:

NSServices

    
        NSMessage
        itemsDroppedOnDock
        NSSendTypes
        
            public.data
        
        NSMenuItem
        
            default
            Open Mail
        
    

Then your Swift app delegate would look like this:

import Cocoa

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

    func applicationDidFinishLaunching(aNotification: NSNotification) {
        NSApp.servicesProvider = self
    }

    @objc func itemsDroppedOnDock(pboard: NSPasteboard, userData: NSString, error: UnsafeMutablePointer) {
        // help from https://stackoverflow.com/questions/14765063/get-dropped-mail-message-from-apple-mail-in-cocoa
        print("dropped types: \(pboard.types)")
        if let types = pboard.types {
            for type in types {
                print(" - type: \(type) string: \(pboard.stringForType(type))")
            }
        }

    }
}

When you drop a mail message on your app's dock, the output will be something like:

dropped types: Optional(["public.url", "CorePasteboardFlavorType 0x75726C20", "dyn.ah62d4rv4gu8yc6durvwwaznwmuuha2pxsvw0e55bsmwca7d3sbwu", "Apple URL pasteboard type"])
 - type: public.url string: Optional("message:%3C2004768713.4671@tracking.epriority.com%3E")
 - type: CorePasteboardFlavorType 0x75726C20 string: Optional("message:%3C2004768713.4671@tracking.epriority.com%3E")
 - type: dyn.ah62d4rv4gu8yc6durvwwaznwmuuha2pxsvw0e55bsmwca7d3sbwu string: Optional("\n\n\n\n\tmessage:%3C2004768713.4671@tracking.epriority.com%3E\n\t\n\n\n")
 - type: Apple URL pasteboard type string: Optional("\n\n\n\n\tmessage:%3C2004768713.4671@tracking.epriority.com%3E\n\t\n\n\n")

Unfortunately, you probably need to figure out how to convert the mail URL "message:%3C2004768713.4671@tracking.epriority.com%3E" into the actual underlying mail file, but it's a start.

Alternatively, if you are willing to accept a drop in your app's window rather than on the dock, you should be able to just use NSDraggingInfo.namesOfPromisedFilesDroppedAtDestination, which is how I expect the Finder is able to copy the mail message when you drop one on a Finder window (note that the Finder does not respond to mail messages being dropped in its dock icon, only when they are dropped on a window).

Edit:

See Dropping promised files on to application icon in Dock on how to get promised file.