How do I programmatically populate switch case values?

Question

I am pulling in a list of allowed system codes for my case statement via JSON. They are brought in as a string that looks like the following:

let validCodesFromJson:String = "001, 002, 003, 004, 005, 007, 008, 090, 091, 092, 096"

I then convert this string into an array with the follwing:

let validCodes:NSArray = validCodesFromJson.componentsSeparatedByString(", ")

I need to get this array of codes into the first case of my switch statement.

switch responseArray[selectedResponseTableRow]["code"]! {
        case validCodes:

            successfulPostAnimation()

        case "006":

            showAlertWindow("Alert", message: "Code was 006", buttonText: "OK")

        default:

           showAlertWindow("Alert", message: "Code was not in the list", buttonText: "OK")
        }

The switch statement works if the code is "006" in every other case it is using default. It works fine if I define all of the codes in the first case instead of using the array. But I need to do this programmatically for this project.

Answer 1

You can use a guard-clause to increase the complexity of your expression for each particular case . For example:

var validCodes = ["001", "002", "003"]

var code = "002"

switch code {
    case let value where (contains(validCodes, value)):
        "Valid code"
    case "006":
        "Bad code"
    default:
        "Default"
}

If you run this in a playground, you'll see "Valid code" .

If you're interested in seeing the grammar/syntax for these kinds of patterns, you can The Swift Programming Language: Statements