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iOS

Posted by Julian Coy
Julian Coy
6,774 Points

A note about enums and raw values...

Code in question:

enum test: Int {
    case first = 1, second = 2, third, fourth
}

test.first.rawValue // 1
test.second.rawValue // 2
test.third.rawValue // 3
test.fourth.rawValue // 4

enum test2: Int {
    case first, second = 2, third, fourth
}

test2.first.rawValue // 0
test2.second.rawValue // 2
test2.third.rawValue // 3
test2.fourth.rawValue // 4

enum test3: Int {
    case first = 1, second = 2, fourth, third = 3
}

// This enum is broken and will result in an error
// Error: Raw value for enum case is not unique
//
// This is because the raw value of 3 is assigned to
// 'fourth' automatically.

enum test4: String {
    case first = "a", second = "b", third, fourth
}

// This enum is broken and will result in an error
// Error: Enum case must declare a raw value when the
// preceding raw value is not an integer

By running these tests, I noted that the enum itself will attempt to assign incrementally increasing values when given a Raw Value of Int from the first assignment statement it sees. Any subsequent assigns must match that formula or will result in an error. Strings, or other types for that matter, require full assignment of raw values for all cases in the enum.

Let me know if I missed anything. I'm trying to figure out all the intricacies of the enum, as I know it can be very powerful.