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

Max Ramirez
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Max Ramirez
iOS Development Techdegree Graduate 17,361 Points

Error with Code, not comping, Optional Values

Hello, My code is not compiling and I do not know why, is there an issue with my code? Please take a look and any assistance is greatly appreciated, I tried using all of the knowledge as shown in the videos, but still no success.

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

}
Chris Sehnert
Chris Sehnert
30,857 Points

"Assign" values to optionals through guard let statements.... = not :

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"] }

2 Answers

Chris Sehnert
Chris Sehnert
30,857 Points

You are welcome Max....BTW...the solution is still less than perfect ...and worth examining....for instance... since the price and pubDate properties are not part of the guard let statement.....there exists the possibility where a dictionary used to instantiate a newBook may have a ["price": 8.0] member or a [pubDate: 12/16/14] member....where the value type associated with the expected key does not match the String? type specified.......

String? means it will accept a String value ...or nil.......

any other value will cause the app to CRASH!!!