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iOS Swift Enums and Structs Enums What is an Enum?

Akos Turi
Akos Turi
7,517 Points
Posted by Akos Turi
Akos Turi
7,517 Points

Default will never be executed

enum Day {
    case Monday
    case Tuesday
    case Wednesday
    case Thursday
    case Friday
    case Saturday
    case Sunday
}


func weekdayOrWeekend(dayOfWeek: Day) -> String {
    switch dayOfWeek {
        case Day.Monday, Day.Tuesday, Day.Wednesday, Day.Thursday, Day.Friday:
            return "It's a weekday"
        case Day.Saturday, Day.Sunday:
            return "It's the weekend"
        default:
            return "Not a valid day"
    }
}

weekdayOrWeekend(Day.Sunday)

the code itself works fine but when i try to give an invalid value, it says default can't be executed and get an error

5 Answers

Steve Hunter
Steve Hunter
57,712 Points

Hi Akos,

The code does work fine. What error value are you trying to submit?

If you send the method something that isn't a valid Day value, the method call will error rather than the default value being used. If you use a valid Day value, then the switch will pick that up accordingly.

I get a warning that the default will never be used, and that's correct; you have created a mutually exclusive set of rules; you can't submit an error into the switch; that will fail at the method call. 

var errorValue: Int
weekdayOrWeekend("Steve") // Cannot convert value of type String to expected argument type Day
weekdayOrWeekend(errorValue) // cannot convert Int to Day

What behaviour were you expecting from this; what's not acting like you wanted it to?

Steve.

Akos Turi
Akos Turi
7,517 Points
Akos Turi
Akos Turi
7,517 Points

i got an warning that default will never be executed, so probably that is your second thought, what you have mentioned. I just do not understand why that code works for Amit perfectly but not for me, why do i get a warning. Thanks for your help in advance

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

I would say that this is a difference between Swift v1 and Swift v2.x which you are running. The later version tightened up on the typing aspects of Swift so there are some real differences between the code Amit is using and yours. Either way, your code works fine; indeed, it is more logical not requiring the default as there cannot be any use for it; if you get beyond the method call, you've done enough testing of the parameter so no default is required.

Steve.

Dar Phan
Dar Phan
1,459 Points
Dar Phan
Dar Phan
1,459 Points

Hey Steve,

I'm running the most recent version and I'm having the error, which I figured was fine. However, when I call a different day my output doesn't change.

For example, I call Friday, it tells me it's a weekday and it shows two warning messages. Then I change it to Saturday, it still says weekday and same warning messages. I change it to none of the days above, output has an error. Why am I changing it from weekend to weekday but the output isn't changing?

Steve Hunter
Steve Hunter
57,712 Points

Can you post your code and I'll take a look.

Thanks,

Steve.

Dar Phan
Dar Phan
1,459 Points
Dar Phan
Dar Phan
1,459 Points 
enum Day {
        case Monday
        case Tuesday
        case Wednesday
        case Thursday
        case Friday
        case Saturday
        case Sunday
}

let days = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"]


func weekedayOrWeekend(dayOfWeek: Day) -> String {

    switch dayOfWeek {
            case Day.Monday, Day.Tuesday, Day.Wednesday, Day.Thursday, Day.Friday, Day.Saturday, Day.Sunday:
                return "It's a Weekday."
            case Day.Saturday, Day.Sunday:
                return "Fuck yeah!"
    default:
        return "Not a Valid Day."
}
}
weekedayOrWeekend (Day.Sunday)
Steve Hunter
Steve Hunter
57,712 Points

Hi Dar,

You have included Saturday and Sunday in your "It's a weekday" switch option so every day of the week will reach that line of code first, outputting "It's a weekday!". Remove Day.Saturday and Day.Sunday from that switch test and the code will then reach the second option.

Let me know how you get on.

Steve.

Akos Turi
Akos Turi
7,517 Points
Akos Turi
Akos Turi
7,517 Points

All hail to Mr. Hunter!!! thanks for your effort

Steve Hunter
Steve Hunter
57,712 Points

Haha! Thank you. :-)

Dar Phan
Dar Phan
1,459 Points
Dar Phan
Dar Phan
1,459 Points

Do'h! Sometimes you just need another set of eyes. Thanks!