A simple way to iterate over linear Int-based enums

EnumSequence.swift

struct EnumSequence<T: RawRepresentable> where T.RawValue == Int {}

extension EnumSequence: Sequence {
    func makeIterator() -> AnyIterator<T> {
        var rawValue = 0

        return AnyIterator {
            let nextCase = T(rawValue: rawValue)
            rawValue += 1
            return nextCase
        }
    }
}