Logging In a User

JAVA

ParseUser.logInInBackground("johndoe", "p@ssw0rd", new LogInCallback() {

    public void done(ParseUser user, ParseException e) {

        if (user != null) {

            // User has logged in successfully.

        } else {

            // Error! Access the "e" variable to find out what.

        }

    }

});

SWIFT

PFUser.logInWithUsernameInBackground("johndoe", password:"p@ssw0rd") {
  (user: PFUser?, error: NSError?) -> Void in
  if user != nil {
    // Do stuff after successful login.
  } else {
    // The login failed. Check "error" variable to see why.
  }

}