Why do we "guard" a name and an age here instead of address?

Ah, now that I have more of a context I can answer your question. It is a matter of opinion, however there are more elegant ways. My personal take on this would be to assign a default value as a fallback ("??"). Then I could have the whole block on one line.

struct Person {
    let givenName: String
    let familyName: String
    let middleName: String?
    var displayName: String {
        // My solution
        return "\(self.givenName) \(self.middleName ?? "") \(self.familyName)"
    }
}

That single-line block would replace that bloggers four-line block.

To clarify though, I think what you are suggesting is more readable than the 'if let/else' method that apple teaches in the 3.1 Docs. I just didn't understand what you were getting at, at first, lol.

Hope this helps,

Charles

This is where I am confused as well. I thought that I understood Guard, until I tried to solve the problem. My solution is the following:

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

    init?(dict: [String: String]){
      guard let priceNew = dict["price"], let pubDateNew = dict["pubDate"] else {
        return nil
      }

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

If you run this solution in xCode you get the following error:

error: value of optional type 'String?' not unwrapped; did you mean to use '!' or '?'? self.author = dict["author"]

My question is: Why not guard the optional values?

A possible explanation is the one I thought last night while showering: Maybe, if we say that price and pubDate are optional, then we might NOT pass a value (nil). But title and author are not optional so we must check for the absence of value, this is why we use guard on these 2 (title, author) instead on price and pubDate.

Was my showering epiphany correct?

Another question:

During

if let variable1 = someOptional 

OR

guard let variable1 = someOptional

isn't the variable1 the unwrapped value of someOptional? If this is the case, what happens if we replace the someOptional with a nonOptional value?

PS: on Pasan's video "Early Exits using Guard" on 0:42 he says: "The expression has to be one that returns an optional value". So how can a non-optional constant return an optional value? Or is it that only non-optional constants that return optional values? Confused! :|

Thanks!