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

Jake White
Jake White
2,108 Points
Posted by Jake White
Jake White
2,108 Points

This compiles on Xcode

But doesn't work here

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

}
func dict(dict: [String: String]) -> Book? {
    guard let title = dict["title"], author = dict["author"] else {
        return nil
    }
    let price = dict["price"], pubDate = dict["pubDate"]

    return Book(title: title, author: author, price: price, pubDate: pubDate)
}

2 Answers

Greg Kaleka
Greg Kaleka
39,021 Points
Greg Kaleka
Greg Kaleka
39,021 Points

Hi Jake,

You need to create a failable initializer for Book, not a function that returns an optional.

Just like any other init method, this one needs to go inside the struct. Other than that, your inner code is pretty close.

failableInit.swift 
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"]
}

Let me know if that makes sense.

Cheers :beers:

-Greg

Jake White
Jake White
2,108 Points
Jake White
Jake White
2,108 Points

Okay, yes thank you that makes sense now!