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

Endi Hıdır
Endi Hıdır
1,762 Points
Posted by Endi Hıdır
Endi Hıdır
1,762 Points

I couldn't understand what this question asked me. Can someone give me a clue or an answer. The code I wrote is below

In the editor, you have a struct named Book which has few stored properties, two of which are optional.

Your task is to create a failable initializer that accepts a dictionary of type [String : String] as input and initializes all the stored properties. (Hint: A failable init method is one that can return nil and is written as init?).

Use the following keys to retrieve values from the dictionary: "title", "author", "price", "pubDate"

Note: Give your initializer argument the name dict

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

    init?(dict: [String: String], title: String, author: String, price: String, pubDate: String) {
        self.title = title
        self.author = author
        self.price = price
        self.pubDate = pubDate
        if let title = dict["title"], let author = dict["author"]{
            let price = dict["price"]
            let pubDate = dict["pubDate"]
            Book(dict: ["My": "Books"], title: title, author: author, price: price!, pubDate: pubDate!)
        }

            return nil

    }

}
Endi Hıdır
Endi Hıdır
1,762 Points
Endi Hıdır
Endi Hıdır
1,762 Points

Thank you so much Amazon Web

1 Answer

Amazon Web
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.a{fill-rule:evenodd;}techdegree
Amazon Web
iOS Development Techdegree Student 4,092 Points
Amazon Web
.a{fill-rule:evenodd;}techdegree
Amazon Web
iOS Development Techdegree Student 4,092 Points

Alright! You don't need to add all the properties in the argument of init method, you only need the dictionary.

init? (dict: [String: String] {
     //The code below belongs here
}

Next you need to get the value of title and author from the dictionary. If these values are nil you need to return nil (because these properties are non optional)

if let title = dict["title"], let author = dict["author"] {
     self.title = title
     self.author = author
}else {
     return nil
}

Finally, you need to get the value of price and pubdate from the dictionary. If these values are nil, no problem! Because these are optionals (so they can have nil values),

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