Xcode Swift Coding Newbie: 'Unterminated string literal' error

I have been reading a new Swift book and I am trying one of the exercises. This particular exercise is a simple Greeting app where you type in your name, click the button and below the button it returns "Hi,...".

This is the code:


This is the Main.storyboard:


View Controller:


Also, I am wondering why when I switch from iPhone 7 view to iPhone SE view, the formatting is completely off. I have everything centred, why would it move off centre when I switch iPhone views.

Not sure if I provided enough information, if not, let me know.

Thanks