I can't use instance member array within property initializer

Question

import UIKit

class ViewController: UIViewController {

    @IBOutlet var Text1: UITextField!
    @IBOutlet var Text2: UITextField!
    @IBOutlet var Text3: UITextField!
    @IBOutlet var Label: UILabel!

    let array = ["Frodo", "sam", "wise", "gamgee"]
    let randomIndex = Int(arc4random_uniform(UInt32(array.count))) //Problem is here

    @IBAction func button(_ sender: Any) {

        Label.text = array[randomIndex]
    }
}

Possible duplicate of [How to initialize properties that depend on each other](https://stackoverflow.com/questions/25854300/how-to-initialize-properties-that-depend-on-each-other) — vadian, Jan 22 '18 at 09:02

score 0 · Accepted Answer · answered Jan 22 '18 at 08:58

You didn't ask any question so I assume you have problem with accessing count of array.

In general you can't access any of instance members until init is completed. There are (at least) three solutions for your problem.

First is to override all init required by UIViewController and set randomIndex there.

Second is to use lazy for randomIndex:

lazy var randomIndex = {
    Int(arc4random_uniform(UInt32(array.count)))
}()

Third is to use some model (class/struct) for those data and inject it to ViewController

score 0 · Answer 2 · answered Jan 22 '18 at 09:05

You cannot run the line to get the random index on the top level of the class.

It must be located within a function / method:

@IBAction func button(_ sender: Any) {
    let randomIndex = Int(arc4random_uniform(UInt32(array.count)))
    Label.text = array[randomIndex]
}

And please conform to the naming convention that variable names start with a lowercase letter (text1, label).

I can't use instance member array within property initializer

2 Answers2