A `safeValue` method for Optional type. It returns an empty value if the wrapped type of the Optional type has one, for example String and Array.

Optional+SafeValue.swift

/// A type that supports an "empty value"
protocol EmptyValuable {
    /// Returns the empty value of `Self`
    static var emptyValue: Self { get }
}

extension String: EmptyValuable {
    static var emptyValue: String {
        return ""
    }
}

extension Array: EmptyValuable {
    static var emptyValue: [Element] {
        return []
    }
}

extension Optional where Wrapped: EmptyValuable {
    /// If `self` is non-`nil`, returns the unwrapped value. Otherwise, returns an empty value of the `Wrapped` type
    var safeValue: Wrapped {
        return self != nil ? self! : Wrapped.emptyValue
    }
}