More on optionals

// MORE ON OPTIONALS
func getHaterStatus(weather: String) -> String? {
    if weather == "sunny" {
        return nil
    } else {
        return "Hate"
    }
}

// For the code to work, the status variable must be marked as optional
// i.e., var status: String?
// Or, type inference must be used as in the below example:
var status = getHaterStatus(weather: "rainy") // status is an optional

// The function below accepts a String but NOT an optional String.
// So, status (an optional) couldn't be passed into it.)
func takeHaterAction(status: String) {
    if status == "Hate" {
        print("Hating")
    }
}

// To ensure that takeHaterAction() receives a non-optional,'
// we use "if let."
// If getHaterStatus returns a value that is not nil,
// haterStatus (a non-optional) can be passed to takeHaterAction()
if let haterStatus = getHaterStatus(weather: "rainy") {
    takeHaterAction(status: haterStatus)
}

// NIL COALESCING
// newStatus is a non-optional because it will receive a value.
// (In this ex. getHaterStatus returns nil so newStatus = "None of..."
let newStatus = getHaterStatus(weather: "sunny") ?? "None of your business"