Swift segue不工作

Question

当用户尝试注册时，不会调用segue。我检查了Parse - 用户的用户名和密码已注册。今天早些时候一切都运转正常。任何想法为什么会这样？我在Stack Overflow上检查了一些解决方案，但没有运气。

if user == nil {
    NSLog("Uh oh. The user cancelled the Facebook login.")

    // Make the label visible when the user cancel the Facebook login
    self.loginCancelLabel.alpha = 1

} else if user.isNew {
    NSLog("User signed up and logged in through Facebook!")

    isFacebookUser = 1

    println("User is registered"); // This print statement prints. 


    // The statement below never gets called/the user profile is never presented. 
    self.performSegueWithIdentifier("jumpToUserProfile", sender: self)
}