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iOS Swift 2.0 Enumerations and Optionals Introduction to Optionals Initializing Optional Values

JUNSEI TEI
JUNSEI TEI
2,055 Points
Posted by JUNSEI TEI
JUNSEI TEI
2,055 Points

Guard Statements in Initializer

CODE CHALLENGE... HELP ME

optionals.swift 
struct Book {
    let title: String
    let author: String
    let price: String?
    let pubDate: String?

    init?(dict: [String: String]) {
        guard  self.title = dict["title"], self.author = dict["author"]
            else{ return nil }
          self.price = dict["price"]
          self.pubDate = dict["pubDate"]

    }

}

1 Answer

Martin Wildfeuer
PLUS
Martin Wildfeuer
Courses Plus Student 11,071 Points
Martin Wildfeuer
Martin Wildfeuer
Courses Plus Student 11,071 Points

You can't really init a class member variable with the guard statement, so the easiest way would be using "helper variables".

struct Book {
    let title: String
    let author: String
    let price: String?
    let pubDate: String?

    init?(dict: [String: String]) {
        guard let title = dict["title"], let author = dict["author"] else {
            return nil
        }

        self.title = title
        self.author = author
        self.price = dict["price"]
        self.pubDate = dict["pubDate"]
    }
}

Hope that helps :)

Martin Wildfeuer
Martin Wildfeuer
Courses Plus Student 11,071 Points
Martin Wildfeuer
Martin Wildfeuer
Courses Plus Student 11,071 Points

You are welcome! I see that you got an answer to the same question in another thread. It says that you don't have to use guard at all. True, there are more ways to address this. However, I do find the guard statement very easy to read, so I'd prefer the way you coded this.

r5
r5
2,416 Points
r5
r5
2,416 Points

Hey, Is it possible with this code to assign the struct Book to a constant an assign your values to title, author etc.? And if so what is the right syntax?

Thanks!