understanding enum:Int in Swift 5

enumIntSwift5.md

I got a curious about how compiler determines a value's rawValue. First, I give you an example code:

enum Rank: Int{
    case Tom
    case Jane
    case Steve, Tim
}

In this situation, Rank.Tom.rawValue is 0, also Rank.Jane.rawValue is equal to 1 (increment as 1). It means, compiler determines rawValue automatically starting from 0, if data type is Int.

Let me give you an another example, I decided another starting rawValue point as 5 like below:

enum Rank: Int{
    case Tom = 5
    case Jane
    case Steve, Tim
}

Then Rank.Jane.rawValue is equal to 6. Also, If I set Jane's rawValue as 10 (keeping Tom = 5), Rank.Steve.rawValue is equal to 11.