\`==\`与\`hashValue`

Fruit.swift

class Fruit:Hashable {
    let name:String
    
    var hashValue: Int {
        return name.hashValue
    }
    
    init(name:String) {
        self.name = name
    }
    
    static func ==(lhs: Fruit, rhs: Fruit) -> Bool {
        return lhs.name == rhs.name
    }
}