Swift 3：Class和Struct可選

Question

我已經很長時間從編碼Obj-c過渡到Swift 3了。 所以我想我理解可選的想法，但是我對這個問題感到困惑。 假設我有一個名為Monster的課程。 我也有一個叫做Town的結構。

struct Town {
    var population: Int = 0
    var name: String?
    var hasSherrif: Bool?
    var hasTheater: Bool?
    var hasTownhall: Bool?
    var hasSchool: Bool?
    var hasGeneralStore: Bool?
    var numOfHomes: Int = 0
}

還有怪物

class Monster {
    var town: Town?
    var name: String?

    func moveToTown(_ thisTown: Town) {
        town = thisTown
        if let strName = name, let strTownName = town?.name {
            print("\(strName) moved to \(strTownName)")
        } else if let strName = name {
            print("\(strName) move to a town with no name")
        } else {
            print("The monster moved to a town. Might help if you give stuff names, just saying.")
        }

    }
}

在moveToTown（_ thisTown：Town）中，如何檢查Monster是否沒有名字，而Town是否呢？ 我想更改此行：

} else if let strName = name {

像

} else if let strName = name && town?.name == nil {

然后添加另一個條件

} else if strName == nil && let strTownName = town?.name {
}

謝謝，如果有什么需要清理的地方，隨時可以批評。

Answer 1

您不能使用town?.name因為town不是可選的。

無需town = thisTown行。 只需將參數命名為town 。

我會這樣寫：

func moveToTown(_ town: Town) {
    if let name = name {
        if let townName = town.name {
            print("\(name) moved to \(townName)")
        } else {
            print("\(name) move to a town with no name")
        }
    } else {
        print("The monster moved to a town. Might help if you give stuff names, just saying.")
    }
}