Original post https://github.com/onmyway133/blog/issues/49
Today someone showed me https://medium.com/@\_Easy\_E/initializing-enums-with-optionals-in-swift-bf246ce20e4c which tries to init enum with optional value.
enum Planet: String {
case mercury
case venus
case earth
case mars
case jupiter
case saturn
case uranus
case neptune
}
extension RawRepresentable {
init?(optionalValue: RawValue?) {
guard let value = optionalValue else { return nil }
self.init(rawValue: value)
}
}
let name: String? = "venus"
let planet = Planet(optionalValue: name)
One interesting fact about optional, is that it is a monad, so it has map and flatMap. Since enum init(rawValue:) returns an optional, we need to use flatMap. It looks like this
let name: String? = "venus"
let planet = name.flatMap({ Planet(rawValue: $0) })
🎉
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