IUO is not Optional

Non-matching-IUO.swift

protocol Countable {
    var count: Int? {get}
}

struct OptionalCount: Countable {
    var count: Int? = 0
}

struct DeadlyCount: Countable { // Type 'DeadlyCount' does not conform to protocol 'Countable'
    var count: Int! = 0 // 1. Candidate has non-matching type 'Int?' <----------
}