Error in Xcode when trying to use a constant property inside a closure

Question

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?

try to capture PLACE_HOLDER as follow: let textFieldOne: UITextField = { [PLACE_HOLDER] — OhadM, Dec 26 '19 at 21:20
My bad, I have updated my question to closure instead of a computed property. — fs_tigre, Dec 26 '19 at 21:33

score 0 · Accepted Answer · edited Dec 26 '19 at 23:21

0

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
}()

edited Dec 26 '19 at 23:21

Lew Winczynski

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answered Dec 26 '19 at 21:17

Shehata Gamal

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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
1

https://theswiftdev.com/2018/12/17/lazy-initialization-in-swift/ and http://www.apeth.com/swiftBook/ch03.html#_lazy_initialization – Shehata Gamal Dec 26 '19 at 21:33
2

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

Error in Xcode when trying to use a constant property inside a closure

1 Answers1