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Jon B.1's avatar
Jon B.1
Collaborator | Level 9
4 years ago

Short-lived token migration in Swift producing nil Client

I'm migrating an old Swift app to SwiftyDropbox 6.0.3 and short-lived tokens with refresh; our app needs offline access.  But with the code changes, I'm getting odd behaviour -- the completion handler in DropboxClientsManager.handleRedirectURL is never being called, with either a success or an error.  It just quietly fails and DropboxClientsManager.authorizedClient remains nil.

 

Here's my code fragment, which is basically the old sample code.  First, I've set the event handler:

 

            NSAppleEventManager.shared().setEventHandler(self,

                                                         andSelector: #selector(handleGetURLEvent),

                                                         forEventClass: AEEventClass(kInternetEventClass),

                                                         andEventID: AEEventID(kAEGetURL))

 

Then, there's the function which now calls authorizeFromControllerV2:

 

    func launchAuthorizeURL() {

        let scopeRequest = ScopeRequest(scopeType: .user, scopes: [], includeGrantedScopes: true)

        DropboxClientsManager.authorizeFromControllerV2(

            sharedWorkspace: NSWorkspace.shared,

            controller: viewController,

            loadingStatusDelegate: nil,

            openURL: { (url: URL) -> Void in

              NSLog("DbXConnect opening Dropbox URL")

              NSWorkspace.shared.open(url)

            },

            scopeRequest: scopeRequest // I've also tried with a nil scopeRequest

        )

    }

 

And the receiving end:

 

    @objc func handleGetURLEvent(_ event: NSAppleEventDescriptor?, replyEvent: NSAppleEventDescriptor?) {

        if let aeEventDescriptor = event?.paramDescriptor(forKeyword: AEKeyword(keyDirectObject)) {

            if let urlStr = aeEventDescriptor.stringValue {

                // It gets here...

                let url = URL(string: urlStr)!

                let oauthCompletion: DropboxOAuthCompletion = {

                    print("HandleGetURLEvent redirect completion handler running")   // It doesn't get here!

                  if let authResult = $0 {

                    switch authResult {

                    case .success (let newToken):

                        print("handleGetURLEvent: Success! User is logged into Dropbox.")

                        /* here I do my own setup */

                        // Launch confirmation page separately

                        NSWorkspace.shared.open(URL(string: "https://mysite/response.html")!)

                    case .cancel:

                        print("handleGetURLEvent: Authorization flow was manually canceled by user!")

                    case .error(let errCode, let description):

                        print("HandleGetURLEvent Error: \(description)")

                    }

                  }

                }

                let bResult = DropboxClientsManager.handleRedirectURL(url, completion: oauthCompletion)

                // this brings your application back to the foreground on redirect

                NSApp.activate(ignoringOtherApps: true)

            }

        }

        client = DropboxClientsManager.authorizedClient

        if (client == nil) {

            // It reports an error here.

        }

    }

 

This code worked fine with the old authorizeFromController call (and still does if I switch back that one call).

 

On a related note -- what's the best practice for how to specify offline token access with SwiftyDropbox?  Is that made available by default with authorizeFromControllerV2?

  • I think I've resolved it -- I'm still not sure why it was interfering with that URL scheme in the main program, but that may be down to the Group Container settings which lump the app and the Finder Sync extension together for communication purposes!

     

    The source of the problem was that the Finder Sync extension was trying to connect to the socket on *its* main thread, and taking a full minute to fail.  By moving the connection attempt off of the main DispatchQueue onto a low-priority one, the problem with Dropbox not being able to get through to the main program vanished.

     

    Strange, but hey, if it works...!

  • Greg-DB's avatar
    Greg-DB
    Icon for Dropbox Staff rankDropbox Staff

    I just gave this a try by setting up a new macOS project with your code snippets here, and it worked successfully for me. It got to "handleGetURLEvent: Success! User is logged into Dropbox.".

     

    Can you let me know what versions of Xcode and macOS you're using? Also, what method did you use to install the SwiftyDropbox library?

     

    The authorizeFromControllerV2 method automatically requests "offline" access.

    • Jon B.1's avatar
      Jon B.1
      Collaborator | Level 9

      Following from my previous update -- this is SwiftyDropbox 6.0.3 installed using CocoaPods, and Xcode 12.5 on Big Sur 11.4.  But as I said, I'm now suspecting that there's something going on elsewhere in my app, blocking the dispatch queue which authorizeFromControllerV2 / handleRedirectURL is trying to use.  Are there guidelines about what parts of the auth process should or shouldn't be called on the main thread?

  • Jon B.1's avatar
    Jon B.1
    Collaborator | Level 9

    Update on this:  turns out the completion handler *was* running consistently, it just took about two minutes to do so, and so other things were timing out as a result!  It looks like something is sitting on the main thread in my app, which was blocking the completion handler from running.  I'm still investigating.

     

     

    Basically, there were more changes than I thought between my old SwiftyDropbox version and 6.0.3.  Rather than having the logic continue in the original thread, I've now refactored so that the code which checks the client status and proceeds to my own completion handler is only executed at the end of the handleRedirectURL completion handler.

     

    But even after these changes, it's still taking about 45 seconds for the handleRedirectURL completion handler to run.  Is there anything I need to know about how 6.0.3 deals with the main queue, which could explain the blocking?  Or is this a problem with the rest of my app?

    • Greg-DB's avatar
      Greg-DB
      Icon for Dropbox Staff rankDropbox Staff

      Thanks for following up. I'm not aware of anything with the SwiftyDropbox SDK itself that would cause that. In my test, for instance, the entire completion handler runs pretty much instantaneously.

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