Initializers may only be declared within a type? How would I declare dict as a type?

Hey Paul Je,

This challenge is asking us to create a failable initializer for the Book struct. The initializer will take a dictionary as its parameter and use that dictionary to provide values to the stored properties of Book. Since it's possible that this dictionary will not have the data necessary to provide values to the Book instance's properties, it is a failable initializer.

We know that the dictionary's type is [String: String] because the challenge says that the keys are Strings and all the types of our properties, which we will be setting from the values, are Strings.

Since the first two properties, title and author, are not of the optional type, they must have a value. Therefore, I created a guard statement to make sure that values for the "title" and "author" keys are not nil. If they are, the initializer will fail and return nil.

The other two properties, price and pubDate are of the String? type. This means they can have a nil value. Therefore, if the value's for the "price" or "pubDate" keys are nil, or if those keys do not exist, then the nil value can be safely accepted by this property.

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"]
    }
}

Good Luck!