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

Yuanzheng Wen
PLUS
Yuanzheng Wen
Courses Plus Student 1,756 Points
Posted by Yuanzheng Wen
Yuanzheng Wen
Courses Plus Student 1,756 Points

Code run in playground, but not accepted by system

I have following code, and run into error saying my init method doesn't accept input var.

optionals.swift 
struct Book {
    let title: String
    let author: String
    let price: String?
    let pubDate: String?
    init? (dict: Dictionary<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"]
    }
}

1 Answer

Nathan Tallack
Nathan Tallack
22,159 Points
Nathan Tallack
Nathan Tallack
22,159 Points

You were close. You should declare your dictionary type with the following syntax in the first line of your init? method.

init? (dict: [String: String]) {

When we are saying a dictionay of key String value String it looks like [String: String]. Take care not to confuse with an array where it would be just [String]. The fact that we have a type then a colon and then a type inside the square brackets make it clear to the compiler that it is a dictionary type not an array type. :)