Explain me optionals meaning and how its build?

In Swift, optionals are a powerful feature designed to handle the absence of a value. An optional is a type that can hold either a value or nil, indicating the absence of a value. This is particularly useful in preventing runtime crashes that occur when a nil value is unexpectedly encountered.

Optionals are built into Swift's type system and are represented using a generic type in the standard library. You can declare an optional by appending a question mark (?) to the type. For example, Int? is an optional integer, which can hold either an integer value or nil.

To access the value stored in an optional, you must "unwrap" it. This can be done safely using the if let syntax, which checks if the optional contains a non-nil value and binds it to a constant if it does. Alternatively, you can use force unwrapping with an exclamation mark (!), but this should be done with caution as it will cause a runtime crash if the optional is nil.

Here's a brief example from the session A Swift Tour: Explore Swift’s features and design:

var optionalInt: Int? = 5

// Safe unwrapping
if let value = optionalInt {
    print("The value is \(value)")
} else {
    print("The optional was nil")
}

// Force unwrapping (use with caution)
let forcedValue = optionalInt!
print("The forced value is \(forcedValue)")

This design helps ensure that your code is robust and less prone to errors related to unexpected nil values.