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

Benjamin Lim
Benjamin Lim
2,747 Points
Posted by Benjamin Lim
Benjamin Lim
2,747 Points

I understand most of this, but will someone explain the last part?

This is the correct answer in which i got from another post on the forum. I understand most of this up till it says self.price = dict["price"] self.pubDate = dict["pubdate"]

Why do we have to specify those strings?

Thanks

optionals.swift 
struct Book {
    let title: String
    let author: String
    let price: String?
    let pubDate: String?
    init?(dict: [String: String]) {

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


    }
}

1 Answer

ianhan3
ianhan3
4,263 Points
ianhan3
ianhan3
4,263 Points

You're accessing those values through the keys. 

//for example
var dict: [String: String] = ["price": "$1.99", "pubDate": "1999"]
dict["price"]
//returns "$1.99"