Different betweenvar modules:[Module] and var modules = [Module]()

App Development
1

I am confusing when declare the variable
the first one:

import Foundation
class ContentModel: ObservableObject {
    @Published var modules:[Module]
    init(){
        getLocalData()
    }
    func getLocalData() {
        
        
    }
}

→ This one return error: ‘self’ used in method call ‘getLocalData’ before all stored properties are initialized

Then I changed to this:

import Foundation
class ContentModel: ObservableObject {
    @Published var modules=[Module]()
    init(){
        getLocalData()
    }
    func getLocalData() {
        
        
    }
}

→ then the error dispeared

Anyone can explain when to decrale
var modules:[Module]
and when to use
var modules=[Module]()

2

In this particular case the declaration:

@Published var modules = [Module]()

says that modules is to be an array of type Module. The opening and closing parenthesis () on the end means to initialise the array.

It can be declared as above, or like this:

@Published var modules: [Module] = []

In both cases the array is created (initialised) but contains nothing.

1 Like
3

thanks for your kindly support. From your explaination, both cases are same, but I dont understant why only the fírst case throws error
When do we declare

var modules:[Module]

instead of

var modeule:[Module] = []
4

This form of declaration

@Published var modules:[Module]

does not include any initialisation. That’s why you got the error message

1 Like
5

That so kind of you Chris :heart_eyes:

6

That and initialization means to set a value

This is saying “hey modules you’re an array of type Module” and that’s it, it has NO value, it just knows the type that it will be

Vs @Published var modules = [Module]()
Says “yo modules, you are an array of Module objects, and are an empty array.

1 Like
7

Thanks you so much bro