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

Make sure you are creating a failable initializer that accepts a dictionary as an argument for initialization

I thought I did it??

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

    init?(withDictionary dict: Dictionary<String, String>) { // See comment below!
        guard let title = dict["title"] else { return nil }
        self.title = title

        guard let author = dict["author"] else { return nil }
        self.author = author

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

5 Answers

Moritz Lang
Moritz Lang
25,909 Points

This is my solution:

init?(dict: [String: String]) {
        // non-optional values
        guard let title = dict["title"] else { return nil }
        guard let author = dict["author"] else { return nil }
        self.title = title
        self.author = author
        // optional values
        self.price = dict["price"]
        self.pubDate = dict["pubDate"]
    }
Moritz Lang
Moritz Lang
25,909 Points

Hi, why do you check the constants that arent optional and not the ones that are optional? :)

By the way: Dictionary<String, String> is not the best way to declare a dictionary of type String: String. It could be easily written like [String: String].

Moritz Lang
Moritz Lang
25,909 Points

Oh, I'm sorry. I interpreted your code wrong. Just give me a moment and I'll provide you with a better solution :)

thks, but that's still giving this error = "Make sure you are creating a failable initializer that accepts a dictionary as an argument for initialization"

Moritz Lang
Moritz Lang
25,909 Points

That's very strange. I can pass this challenge with exactly the code I've written above. Maybe you need to reload the challenge? :)

ok Bud

you were right! Don't know why it freezes