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iOS Swift 2.0 Enumerations and Optionals Introduction to Optionals Nil Values in Collections

Joe Scotto
Joe Scotto
8,282 Points
Posted by Joe Scotto
Joe Scotto
8,282 Points

Why can I not assign "cast" to a variable before using it in the if let?

I have solved the challenge but am curious as to why one version works, and the other does not.

Working code 

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

error: initializer for conditional binding must have Optional type, not 'String'

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

1 Answer

Jhoan Arango
Jhoan Arango
14,575 Points
Jhoan Arango
Jhoan Arango
14,575 Points

Hello:

As the error message suggest, it tells you that it "must" be an optional type, and not a "String". At some point in your chain, it stops being an optional, because you already unwrapped it. Therefore it stops the "unwrapping" process. 

if let movie = movieDictionary["Spectre"],
    let cast = movie["cast"],
    let lead = cast[0] { // This returns a String, which is the value you were looking for, and it should be outside the chain.
    leadActor = lead
}

I hope this helps you.

Good luck