Programming in Swift · Challenge: More Optionals | Ray Wenderlich

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1
This is a companion discussion topic for the original entry at https://www.raywenderlich.com/5994-programming-in-swift/lessons/26
2

Could I use shadowing in this challange?
like:
var myFavouriteSong: String? = “Burns” //nil

if let myFavouriteSong = myFavouriteSong {
print(“My favourite song is (myFavouriteSong)”)
} else {
print(“No favourite song”)
}

print(myFavouriteSong)

3

Yes! Shadowing is always an option when using if let. It’s a stylistic preference, so the decision is up to you. :]

4

Thank you. I love what you guys are doing!

1 Like
5

How do I use a guard statement for the question of the first challenge?

Using your myFavoriteSong variable from the previous challenge, use optional binding to check if it contains a value. If it does, print out the value. If it doesn’t, print “I don’t have a favorite song.”

let myFavoriteSong: String? = nil
// my attempt at using a guard statement:
guard let thisSong = myFavoriteSong else { print("I don't have a favorite song.") return } 
print("\(thisSong) is my favorite song.")

// answer
if let song = myFavoriteSong {
    print("\(song) is my favorite song.")
} else {
    print("I don't have a favorite song.")
}

Am I unable to use a guard let statement outside of a function?

6

Hi! You can use a guard statement outside of a function! You just need a different way to exit the else clause. Some options:

  • return - You know this one already! You can use it in functions.
  • break or continue - You can use these in loops
  • fatalError() - You can use this one anywhere, but it will crash your app (or playground) if the optional is nil. It can be a quick way to make sure optionals you need to have a value actually do.

Usually, though, you’re not going to be using guard or guard let outside of functions.

1 Like
7

You guys do a great Job explaining concepts!
I was wondering if there was an easier way to do the middle exercise.
But you guys didn’t do the middle exercise for Optionals.

8

@jessycatterwaul @catie Do you have any feedback about this? Thank you - much appreciated! :]

9

Hey!

First, you need to change myFavoriteSong from a constant to a variable:

var myFavoriteSong: String? = "November Rain"

Then, you could either use if let binding, discarding the value if there is one, using an underscore…

if let _ = myFavoriteSong {
  myFavoriteSong = nil
} else {
  myFavoriteSong = "Genghis Khan"
}

…or, you could use the conditional operator:

myFavoriteSong =
  myFavoriteSong == nil
  ? "Electric Feel"
  : nil