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

An Optional variable may contain a value or may be not

case 1: var myVar:String? = "Something"

case 2: var myVar:String? = nil

now if you ask myVar!, you are telling compiler to return a value in case 1 it will return "Something"

in case 2 it will crash.

Meaning ! mark will force compiler to return a value, even if its not there. thats why the name Force Unwrapping.