Parse iOS SDK - Login using Mobile phone verification code like Watsapp - ios

Question

How to implement login mechanism with mobile verification code.
SignUp (New User with New Mobile Number)
I can able to do this for signup user by generating a random password after verifying code send to his mobile number.
Login (Existing User with Mobile Number)
But don't knows how to implement this. I cant use changepassword method because it works only for an already logged in user.
Setting the Current User
Saw this Method in Parse Documentation. Can I use this method. If yes, how can I get session token.
[PFUser becomeInBackground:#"session-token-here" block:^(PFUser *user, NSError *error) {
if (error) {
// The token could not be validated.
} else {
// The current user is now set to user.
}
}];

Answer 1

Successfully changed the password without login calling cloud code from ios and then logged in with a new password.
iOS Code
[PFCloud callFunctionInBackground:#"assignPasswordToUser" withParameters:#{#"username":[self generateUsername],#"password":loginModel.verficationCode} block:^(id object, NSError *error) {
if(!error)
{
NSLog(#"Assign New Password Success");
[self doLogin];
}else{
NSLog(#"Assign New Password Failed");
[self handError:error];
}
}];
Cloud Code
Parse.Cloud.define("assignPasswordToUser", function(request, response){
Parse.Cloud.useMasterKey();
var query = new Parse.Query(Parse.User);
query.equalTo("username", request.params.username);
query.first({
success: function(theUser){
var newPassword = request.params.password;
console.log("New Password: " + newPassword);
console.log("set: " + theUser.set("password", newPassword));
theUser.save(null,{
success: function(theUser){
// The user was saved correctly
response.success(1);
},
error: function(SMLogin, error){
response.error("save failure");
}
});
},
error: function(error){
response.error("error");
}
});
});

Answer 2

Assuming your wanted to allow something like registering a new device by scanning a QR Code or something shown on an existing device, you could do that without having to change the password as follows:
User class extra properties:
loginValidation: String
loginValidationExpiry: DateTime
You would use something like a 1 or 2 minute expiry to make things safer, making sure you create the Date using server-time in a Cloud Function. You could generate a guid/uuid for the code and create the QR code on an existing authenticated platform.
On the new device after reading the QR Code you could call this cloud function:
Parse.Cloud.define("validateLoginCode", function(request, response) {
Parse.Could.useMasterKey();
var username = request.params.username;
var validationCode = request.params.validationCode;
var query = new Parse.Query(Parse.User);
query.equalTo("username", username);
query.equalTo("loginValidation", validationCode);
query.first({
success: function(user) {
if (user) {
var expiry = user.get("loginValidationExpiry");
var now = new Date();
if (expiry > now) {
// code is valid, get token, only valid because
// we got user with master key
response.success({ token: user.getSessionToken() });
} else {
response.error("code expired");
}
} else {
response.error("invalid user/code");
}
},
error: function(error) {
response.error("error");
}
});
});
You could now use becomeInBackground:block: method in your calling code.