Xcode 9 and Xcode 10 giving different results, even with same swift version

Question

I am running this code in both xcode 9.3 and xcode 10 beta 3 playground

import Foundation

public protocol EnumCollection: Hashable {
    static func cases()         


        

Answer 1

If you use hashValue of an enum to determine case values (position or id), it's a wrong approach since it doesn't guarantee to return sequential int values, 0,1,2... It is not working anymore from swift 4.2

For example, If you use an enum like this :

enum AlertResultType {
    case ok, cancel 
}

hashValue of this enum might return a large int value instead of 0 (ok) and 1 (cancel).

So you may need to declare the enum type more precisely and use rowValue. For example

enum AlertResultType : Int {
    case ok = 0, cancel = 1
}