How to run Asynchronous function in a Uibutton in swift - ios

Question

I want the getUserToken function and userLogin function to run before the next line which is the Firebase Authentication. For it to run ansynchronous
#IBAction func loginButtonPressed(_ sender: UIButton) {
self.showSpinner(onView: self.view)
guard var phoneNumber = phoneTextField.getRawPhoneNumber() else { return }
phoneNumber = "+234\(phoneNumber)"
guard var userPhoneNumber = phoneTextField.getRawPhoneNumber() else { return }
userPhoneNumber = "234\(userPhoneNumber)"
guard let userName = nameTextField.text else {return}
print(phoneNumber)
getUserAcessToken()
userLogin()
//Validate Required fields are mnot empty
if nameTextField.text == userName {
//Firebase Manipulation
PhoneAuthProvider.provider().verifyPhoneNumber(phoneNumber, uiDelegate: nil) { (verificationId, error) in
if error == nil {
print(verificationId!)
//UserDefaults Database manipulation for Verification ID
guard let verifyid = verificationId else {return}
self.defaults.set(verifyid, forKey: "verificationId")
self.defaults.synchronize()
self.removeSpinner()
}else {
print("Unable to get secret verification code from Firebase", error?.localizedDescription as Any)
let alert = UIAlertController(title: "Please enter correct email and phone number", message: "\n", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
self.present(alert, animated: true, completion: nil)
return
}
}
}
let OTPRequestVC = storyboard?.instantiateViewController(withIdentifier: "OTPRequestViewController") as! OTPRequestViewController
OTPRequestVC.userId = userId
OTPRequestVC.userEmailData = userEmail
self.present(OTPRequestVC, animated: true)
}
I want the two functions to run asynchronously before the firebase auth.

Answer 1

Its not a good idea to run the time consuming functions on the main thread.
My suggestions would be.
getUserAcessToken() and userLogin() functions Should have a callback. Which will make those functions run on a different thread (I believe those functions are making api call which is done in the background thread)
You could call userLogin() in the completion handler of getUserAcessToken() and then firebaseAuth in the completion handler of getUserAcessToken().
This will make sure that the UI is not hanged till you make those api calls and the user will know that something is going on in the app and the app is not hanged.

Answer 2

Without reproducing the entire intended functionality, the pattern you want to follow is:
func loginButtonPressed(_ sender: UIButton) {
// Any immediate changes to the UI here
// ...
// Start time consuming task in background
DispatchQueue.global(qos: .userInitiated).async {
getUserAccessToken()
userLogin()
// Make your Firebase call
PhoneAuthProvider.provider().verifyPhoneNumber(phoneNumber, uiDelegate: nil) { (verificationId, error) in
// Any response validation here
// ...
DispatchQueue.main.async {
// Any UI updates here
}
}
}
}