Write an iPhone application

I want to make an login app which generates One time password (OTP) when you click on forgot password button, so here is an explanation that how an app should function. 1- 1st view controller should contain a login page with username and password label, it should have a login and forgot password button. 2- login credentials should be username as admin and password as password, then if you click on forgot password it should generate one time password(OTP) to our mobile phone. 3- then 3 view controller that is when you click forgot password, when we receive OTP we should enter the OTP and then we should get an page as welcome. 4- when we enter correct login credentials then we should directly get a welcome page.