Swift + Firebase模拟登录错误

Question

iOS rookie here struggling through the early stages of an app that was initially led by a mentor. Issue at the moment occurs in the login view controller:

                override func viewDidAppear(animated: Bool) {
                super.viewDidAppear(animated)
                let myRootRef = Firebase(url:"https://xxxx.firebaseio.com")
                if myRootRef.authData.uid != nil {
                self.performSegueWithIdentifier("loginToGreet", sender: nil)

                  }

Error message beside the second to last line reads "Thread 1: EXC_BAD_INSTRUCTION and below reads "fatal error: unexpectedly found nil while unwrapping an Optional value(lldb)"

This was working when we initially put the project on the shelf. The next chunk of code, if it matters:

    @IBAction func loginPress(sender: UIButton) {
    let myRootRef = Firebase(url:"https://xxx.firebaseio.com")
    myRootRef.authUser(self.patientLoginName.text, password:self.patientLoginPassword.text,
        withCompletionBlock: { error, authData in
            if error != nil {
                // There was an error logging in to this account
                print(error)
            } else {
                // We are now logged in
                print(authData)
                self.performSegueWithIdentifier("loginToGreet", sender: nil)
            }
    })

Answer 1

Try

  if myRootRef.authData != nil {
     self.performSegueWithIdentifier("loginToGreet", sender: nil)
  }

authData might be nil and you are checking for authData.uid. Since authData is nil it will crash at the uid access so change your error checking like above.