使用parse.com在后台注销

Question

I am new to creating apps and am trying to make an app that uses parse.com for logging in and out using Xcode 7 and Swift. I have so far made sign up and login screens and a home screen with, so far, only a sign out button. I have an IBAction method called "signOut" that is triggered when the sign out button is pressed. Inside it I have just two lines of code:

self.performSegueWithIdentifier("segue that goes back to login screen", sender: self)
PFUser.logOutInBackground()

This works fine when connected to the internet, but when offline the screen freezes for 10-20 seconds while the app tries to connect to the network and then switches back to the login screen. I want it to switch to the login screen and then logout and I do not understand why it does not. I have even tried moving PFUser.logOutInBackground() to the viewWillAppear and the viewDidLoad methods of my login screen's view controller and still had the same problem. Perhaps what confuses me most about this is that any code after the logout command continues to be executed while the app tries to connect to the network even though the view does not change. Any help with this issue would be greatly appreciated. Thanks.

Answer 1

Try this:

PFUser.logOutInBackgroundWithBlock({ (error: NSError?) -> Void in
    if let error = error {
        // Handle error
    } else {
        self.performSegueWithIdentifier("unwindToLoginViewController", sender: self)
    }
})

Answer 2

You need to make sure that performSegueWithIdentifier is run on the main thread which is responsible for updating the UI

   dispatch_async(dispatch_get_main_queue()) {
self.performSegueWithIdentifier("segue that goes back to login screen", sender: self)
}

PFUser.logOutInBackground()