Swift 3：Class和Struct可选

Question

I'm transitioning to Swift 3 from coding Obj-c for a long time. So I think I understand the idea of optionals but I'm confused on this problem. Say I have a class called Monster. And I also have struct called Town.

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
}

and Monster...

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.")
        }

    }
}

In moveToTown(_ thisTown: Town), how can I check if Monster has no name but Town does? I'd like to change this line:

} else if let strName = name {

to something like

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

and then add another conditional

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

Thanks and if there's anything in general that could be cleaned up feel free to critique.

Answer 1

You can't use town?.name because town is not optional.

And no need for the town = thisTown line. Just name the parameter as town .

I would write it this way:

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.")
    }
}