title: Swift - how to transfer from one view controller to another?
body: <p>Back to my first swift app, I'm doing the sign in/sign up part, and basically the design with the view controllers so far are:</p>
  
  <p><strong>Welcome screen (sign in/sign up buttons) - Sign in - Sign up - Main Program</strong></p>
  
  <p>I got to the part where in the sign up view controllers, if the user misses one of the required field blanks and they click the button "submit", they will be prompted and back to the current view controller (sign up) to fill the missing fields. Now I want to set that when all the fields are filled, what line of code can I use so when they click the button "submit" it will head back to the welcome screen, so they can sign in afterwards?</p>
  
  <p>Similarly, I got all the the part to check if the user enters correct user name and password, so when they entered the wrong info, they will be prompted and hack to the current view controller (sign in), and how can I do so if they entered the correct user name - password, it will head to the main program view controller (the 4th one)</p>
  
  <p>If what I said above is confusing, I'll post my current controllers and the related code in here. Anyone has any idea? Again, this is my first program so it'd mean very much if I can get some helps from you. Thank you for reading.</p>