Hi folks,

I'm trying to create something like the following:

struct someView: View {
   @FetchRequest(sortDescriptors: [SortDescriptor(\.date)]) var books: FetchedResults<Book>
   let bookCategories = BookCategories.booksByDate(books: books)

   var body: some View {
       // ...
     }
}

The problem is that bookCategories line returns the following error.

Cannot use instance member 'todos' within property initializer; property initializers run before 'self' is available

It works successfully if I place let bookCategories = inside the body, but somehow that seems...inelegant(?) Is that the done way?

Similarly, I can get it working by creating an initializer, but I have to:

• Initialize the fetchrequest inside the init too
• Assign a default value to bookCategories
• Therefore, change bookCategories from let to var

All of which seems clumsy.

So I guess the short version of this question is: how do you elegantly initialize variables that rely on other variables?

You can't use variables of property wrappers inside init of a View. Explanation is here.

What you can do is: Fill the variables with the .onAppear modifier.

Hi @Hatsushira - thanks for the response. I like the idea, but moving the let bookCategories... to a .onAppear on the list gives a "cannot find bookCategories in scope" error when referencing it?

Hello @baggage, Hatsuhira didn't say to place the "let bookCategories" in the .onAppear, what he meant is

change your let into a var (keep it in the main struct not in the body)

var bookCategories: BookCategories

and in the .onAppear add

bookCategories = BookCategories.booksByDate(books: books)
// or
bookCategories = .booksBydate(books: books)

That's the best I can guess with the code you presented :)

@delawaremathguy Ach - can't believe I didn't think of that! You're right of course. Many thanks, much appreciated!