Error Handling

enum NumberError: Error {
    case one, two, three, four
}

func checkNumber(number: Int) throws -> Int {
    switch number {
    case 1:
        throw NumberError.one
    case 2:
        throw NumberError.two
    case 3:
        throw NumberError.three
    case 4:
        throw NumberError.four
    default:
        return 5
    }
}

func errorHandle(error: Error) {
    guard let error = error as? NumberError else {
        print("Unkown error")
        return
    }
    switch error {
    case .one:
        print("one Error")
    case .two:
        print("two Error")
    case .three:
        print("three Error")
    case .four:
        print("four Error")
    }
}


do {
    let a = try checkNumber(number: 4)
    print(a)
} catch let error {
    errorHandle(error: error)
}