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Alexandre Chris
4,042 PointsCode Challenge init?
I dont understand what we are doing in this code challenge and why do we need to initialize in this struct?
3 Answers
Corey F
Courses Plus Student 6,450 PointsOk the code challenge wants us to set up an initializer that accepts dictionary keys.
Remember dictionaries by definition are optionals. We ask for a particular value using a key, but there's a chance this key might not exist and be nil.
It doesn't matter if price or pubDate are nil, since they are optional strings and can take nil values. Title and author aren't optionals , they cannot accept nil and require you need to unwrap the optionals before you can use them.
I'd rather not just give you the answer. So I'm going to give you the way you should never solve this, using force unwrapping (!) . Remember this leads to problems. If it turns out a value is nil... we're screwed.
struct Book {
let title: String
let author: String
let price: String?
let pubDate: String?
init?(dict: [String : String]) {
self.title = dict["title"]!
self.author = dict["author"]!
self.price = dict["price"]
self.pubDate = dict["pubDate"]
}
}
DO NOT DO THIS!
The real answer looks kinda similar. But you can't use (!). So
= dict["title"]!
= dict["author"]!
will not be part of the actual solution. The correct answer requires us to first use another better method we learned to unwrap.
Corey F
Courses Plus Student 6,450 PointsYour just about there
No need to use force unwrapping (!) .Almost never use it. price and pubDate can accept optionals.
And your missing initializing 2 properties So
self.title = ___
self.author = ____
self.price = dict["price"]
self.pubDate = dict["pubDate"]
So fill in the blanks with the stuff you created for use in your guard statement.
David Sparks
Courses Plus Student 8,657 Pointsstruct Book { let title: String let author: String let price: String? let pubDate: String?
init?(dict: [String : String]) {
guard let title = dict["title"], author = dict["author"] else {
return nil
}
self.price = dict["price"]!
self.pubDate = dict["pubDate"]!
}
}
Is closer but can't get this to work either.
Alexandre Chris
4,042 PointsAlexandre Chris
4,042 PointsThank you for your answer :)) it makes it all more clear now.