enum Season {
    case summer, fall, winter, spring, none

    init(name: String) {
        switch name.lowercased() {
            case "summer": self = .summer
            case "fall":   self = .fall
            case "winter": self = .winter
            case "spring": self = .spring
            default: self = .none
        }
    }
}

let winter = Season(name: "winter")
//winter is Season.Winter

print("winter is \(winter)")