Custom unwrapper
The Optional type is an enumeration with two cases. .none is equivalent to the nil literal. .some(Wrapped) stores a wrapped value. You must unwrap the value of an Optional before you can use it.
Common ways to unwrap an Optional safely are:
- Optional Binding:
if let ... - Optional Chaining:
if one?.two?... - Nil-Coalescing:
let a: Int = optional ?? 0 - Unconditional Unwrapping:
let number = Int("42")!
Another method to safely unwrap an Optional is a combination of extension and Nil-Coalescing. Here is a simple extension which allows us to safely unwrap String:
extension Optional where Wrapped == String {
var unwrapped: String {
return self ?? ""
}
}
let a: String?
if a.unwrapped.isEmpty == 0 {
print("Oh, no! It's empty!")
}