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iOS Enumerations and Optionals in Swift Introduction to Optionals Nil Values in Collections

Posted by Chigozie Ofodike
Chigozie Ofodike
11,197 Points

Issa optional binding problem.

Hi, I'm not sure what im doing right and doing wrong.

optionals.swift 
let movieDictionary = ["Spectre": ["cast": ["Daniel Craig", "Christoph Waltz", "Léa Seydoux", "Ralph Fiennes", "Monica Bellucci", "Naomie Harris"]]]

var leadActor: String = ""

// Enter code below
if let movie = movieDictionary["Spectre"],
    let actors = movieDictionary["cast"]{
    let leadActor = actors["Daniel Craig"]
}
Leong Sze Kim
Leong Sze Kim
9,179 Points

What are you trying to do?

Chigozie Ofodike
Chigozie Ofodike
11,197 Points

In the editor, you have a pretty complex dictionary representing a movie. It contains a nested dictionary, which itself contains an array of Strings as a value.

Your job is to assign the string containing the value for the lead actor (which for the sake of the example is at position 0 in the array) to the variable leadActor.

Since dictionaries return optional values, you will have to use an if let statement to unwrap each consecutive operation.

That's the entire challenge, i thought i was doing it right, but i cant figure out how to access the array

3 Answers

Margarita Garmutė
Margarita Garmutė
2,136 Points
Margarita Garmutė
Margarita Garmutė
2,136 Points

if let movieDictionary = movieDictionary["Spectre"], let movieCast = movieDictionary["cast"] { leadActor = movieCast[0] }

Leong Sze Kim
Leong Sze Kim
9,179 Points
Leong Sze Kim
Leong Sze Kim
9,179 Points

An example for your reference

let movieDictionary = ["Spectre": ["cast": ["Daniel Craig", "Christoph Waltz", "Léa Seydoux", "Ralph Fiennes", "Monica Bellucci", "Naomie Harris"]],"Spider-Man:Homecoming": ["cast": ["Tom Holland", "Michael Keaton", "Robert Downey"]]]

var leadActor: String = ""

if let movie = movieDictionary["Spider-Man:Homecoming"]{
    if let movieCast = movie["cast"] {
        leadActor = movieCast[0]
    }
}
Chigozie Ofodike
Chigozie Ofodike
11,197 Points

I got it using this method, but my problem is that I want to do it all on one line, without the pyramid effect. Is there a way to do so?

Leong Sze Kim
Leong Sze Kim
9,179 Points
Leong Sze Kim
Leong Sze Kim
9,179 Points

Sorry, I'm not sure, but why you want to do it in one line, don't you think do it under one line will be ambiguous?