How to Login Registered Users to a Backendless App Using the User Login API

Backendless.UserService.login("green.goblin@backendless.com", "sp1dey",
   object : AsyncCallback<BackendlessUser> {
       override fun handleResponse(user: BackendlessUser?) {
           Log.i(TAG, "User has been logged in")
       }

       override fun handleFault(fault: BackendlessFault?) {
           Log.e(TAG, fault?.message)
       }
   })

[Backendless.shared.userService loginWithIdentity:@"spidey@backendless.com" password:@"greeng0blin" responseHandler:^(BackendlessUser *loggedInUser) {
    NSLog(@"User has been logged in: %@", loggedInUser);
} errorHandler:^(Fault *fault) {
    NSLog(@"Error: %@", fault.message);
}];

Backendless.shared.userService.login(identity: "spidey@backendless.com", password: "greeng0blin", responseHandler: { loggedInUser in
    print("User has been logged in: \(loggedInUser)")
}, errorHandler: { fault in
    print("Error: \(fault.message ?? "")")
})

const Backendless = require('backendless')
/*
 Or use `import Backendless from 'backendless'` for client side.
 If you don't use npm or yarn to install modules, you can add the following line
 <script src="//api.backendless.com/sdk/js/latest/backendless.min.js"></script>
 to your index.html file and use the global Backendless variable.
*/

Backendless.initApp('YOUR_APP_ID', 'YOUR_JS_API_KEY')

const onSuccess = user => {
  console.log('User has been logged in:\n', user)
}

const onError = error => {
  console.error('Server reported an error: ', error.message)
  console.error('error code: ', error.code)
  console.error('http status: ', error.status)
}

Backendless.UserService.login('spidey@backendless.com', 'greeng0blin')
  .then(onSuccess)
  .catch(onError)

Backendless.UserService.login("green.goblin@backendless.com", "sp1dey").then(
   (user) => print("User has been logged in"));