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Can someone be so kind and explain why do I get a squiggly error in Xcode when I try to use a constant property inside a closure?

I need to use a constant property in multiple UITextFields so I set PLACE_HOLDER to be a that constant but I get the following squiggly error when I try to use it inside a closure.

Value of type '(UserInputViewController) -> () -> UserInputViewController' has no member 'PLACE_HOLDER' 

class UserInputViewController: UIViewController{
  // constant   
  let PLACE_HOLDER = "Some Text"

  // computed property for textField
  let textFieldOne: UITextField = {

    let textField1 = UITextField()
    textField1.placeholder = PLACE_HOLDER // error here
    // some other styles

    return textField1
  }()

  override func viewDidLoad(){}
}

Any idea why?

Sh_Khan
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fs_tigre
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1 Answers1

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If you are about to access any property of your ViewController inside a closure before ViewController's initialisation, then you need to declare that variable as lazy:

lazy var textFieldOne: UITextField = { 
    let textField1 = UITextField()
    textField1.placeholder = self.PLACE_HOLDER  
    return textField1
}()
Lew Winczynski
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Sh_Khan
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  • @ Sh_Khan - Everything seem to be working after changing `let textFieldOne:UITextField = {}` to `lazy var textFieldOne:UITextField = {}` II don't quite understand `lazy variables` yet, is there something I should be aware in the meantime? Thanks – fs_tigre Dec 26 '19 at 21:30
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    https://theswiftdev.com/2018/12/17/lazy-initialization-in-swift/ and http://www.apeth.com/swiftBook/ch03.html#_lazy_initialization – Sh_Khan Dec 26 '19 at 21:33
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    In your original definition of textField1 you are referencing PLACE_HOLDER, which WILL BECOME a property once init() has been executed ( You can't access properties before init has completed). Without lazy you are referencing the property before it exists. `lazy` allows you to delay creating the property until you use it. – Mozahler Dec 26 '19 at 21:36