How a constant of class instance is declared without initialization?

Question

In this video, teacher declared 
let vendingMachine: VendingMachine
but my understanding is all instance of a class need to initialized
in this case in VendingMachine class we have 
required init(inventory: [VendingSelection: VendingItem]) {
        self.inventory = inventory
    }
How the declaration without initialization work?
Please fulfill my understanding

Rodrigo Chousal · Accepted Answer

Hey Jiranan,
When creating objects or variables, we use two steps: first, we declare the variable, and then we initialise the variable. However, these steps don't necessarily need to be performed on the same line of code. For instance:
```Swift
let vendingMachine: VendingMachine = VendingMachine(inventory: [someSelection: someItem]) // Two steps, one line
// We can also separate this line into the two steps it is actually doing under the hood:
let vendingMachine: VendingMachine // Declaring variable
vendingMachine = VendingMachine(inventory: [someSelection: someItem]) // Initialising variable
```
Both do the exact same thing, except the first one is condensed into a single line. You can read more on declaration and initialisation of variables here (https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Properties.html) and here (https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Initialization.html).
Hope this helps, 
Rodrigo

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jiranan supawong

jiranan supawong

How a constant of class instance is declared without initialization?

1 Answer

Rodrigo Chousal

Rodrigo Chousal

jiranan supawong

jiranan supawong