What does an exclamation mark mean in the Swift language?

Question

The Swift Programming Language guide has the following example:

class Person {
    let name: String
    init(name: String) { self.name = name }
    var apar         


        

Answer 1

If you're familiar with C#, this is like Nullable types which are also declared using a question mark:

Person? thisPerson;

And the exclamation mark in this case is equivalent to accessing the .Value property of the nullable type like this:

thisPerson.Value