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

Pranav Mahajan
Pranav Mahajan
2,272 Points
Posted by Pranav Mahajan
Pranav Mahajan
2,272 Points

The question is not very clear to me

The init? is suppose to return nil. Then why do we need the keys of the dictionary?

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

init?(dict : [String : String]){
    if let title = dict["title"], let author = dict["author"]{
        return nil}
    //  title = dict[""]
    // author = dict["author"]
    //price = dict["price"]
    //pubDate = dict["pubDate"]
}

}

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

    init?(dict : [String : String]){
        if let title = dict["title"], let author = dict["author"]{
            return nil}
        //  title = dict[""]
        // author = dict["author"]
        //price = dict["price"]
        //pubDate = dict["pubDate"]
    }
}

1 Answer

Daniel Santos
Daniel Santos
34,969 Points
Daniel Santos
Daniel Santos
34,969 Points

Pranav,

This is what worked for me, analyze it and let me know if you don't understand my solution:

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

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

    }

-Dan

Pranav Mahajan
Pranav Mahajan
2,272 Points
Pranav Mahajan
Pranav Mahajan
2,272 Points

Thanks. I understood the logic by reading your code.

I thought that ?init can only return nil. Yes it can(which is the error scenario), but we have to handle the happy scenario as well. I thought ?init isn't meant for writing code for happy scenario & I was wrong.

Daniel Santos
Daniel Santos
34,969 Points

Great that you understand!