Welcome to the Treehouse Community
Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.
Looking to learn something new?
Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.
Start your free trialMonzer Selim
Courses Plus Student 3,849 Pointshow to Make sure that the initializer returns a valid instance given a valid dictionary?
can u help me with that ?
struct Book {
let title: String
let author: String
let price: String?
let pubDate: String?
init?(dict: [String:String]) {
guard let title = dict["title"] , let author = dict["author"] else { return nil }
self.price = dict["price"]
self.pubDate = dict["pubDate"]
return nil
}
}
1 Answer
Steven Deutsch
21,046 PointsHey Monzer Selim,
Remember that the job of the initializer is to make sure that all of the instance's properties have values. You're on the right track, you just need to finish assigning the values you unwrapped with the guard statement to their properties.
struct Book {
let title: String
let author: String
let price: String?
let pubDate: String?
init?(dict: [String:String]) {
/* Looking up values in dict w/ key always returns optional.
Here we unwrap because title & author cannot be optional. */
guard let title = dict["title"] , let author = dict["author"] else { return nil }
/* We now assign those non-optional values to their
corresponding non-optional properties */
self.title = title
self.author = author
// These two properties accept optional values
self.price = dict["price"]
self.pubDate = dict["pubDate"]
}
}
You may also notice that I removed the double return nil
statement. We only want to return nil if we are unable to optional bind one of the values that we need to assign to the instance's non-optional property.
Good Luck