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iOS Enumerations and Optionals in Swift Introduction to Optionals Early Exits Using Guard

Adam Petritsis
Adam Petritsis
2,942 Points

Failable initialiser error

In the exercise following this video, the same error occurs as the one at the end of this video, when we add the failable initialiser. At the return line in the function, it gives an error of "extra argument " bla bla" in call". How do we fix this? In this video, we just deleted the initialiser, however if we want the initialiser what do we do?

2 Answers

Hello Adam,

This is an example from the exercise of the failable initializer:

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"]
    }
}

Maybe this helps to show you how to implement one.

-Dan

Von Chucwuemeca
Von Chucwuemeca
4,746 Points

Here is my solution which is the same as above, the structure is slightly different for better comprehension.

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

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

        self.title = title
        self.author = author
        self.price = dict["price"]
        self.pubDate = dict["pubDate"]
        }
}