I'm trying to make a Login alert in SWIFT but somehow the code doesn't work-CodePudding

@IBAction func login(_ sender: Any) {

     PFUser.logInWithUsername(inBackground: self.txtEmailSignin.text!, password: self.txtPasswordSignin.text!) {

        (user: PFUser?, error: Error?) -> Void in
        if user != nil {
            self.displayAlert(withTitle: "Login Successfully", message: "")
        } else {
            self.displayAlert(withTitle: "Error", message: error!.localizedDescription)
        }
    }
}

CodePudding user response：

First of all, You need to represent the code properly. Your provided code is difficult to understand.

CodePudding user response：

When ever you want to update any UI element in iOS app, the UI should be always updated in the main queue.

Note: Here in your sample code you are performing login request in the background thread it seems. So you are required to update the alert UI in the main thread.

@IBAction func login(_ sender: Any) {

PFUser.logInWithUsername(inBackground: self.txtEmailSignin.text!, password: self.txtPasswordSignin.text!) {
    (user: PFUser?, error: Error?) -> Void in
    if user != nil {
        DispatchQueue.main.async {
            self.displayAlert(withTitle: "Login Successfully", message:"")
        }
    } else {
        DispatchQueue.main.async {
            self.displayAlert(withTitle: "Error", message: error!.localizedDescription)
        }
    }
}}