Escaping closure swift3

Question

I am having an issue regarding closure escaping.The closure is defined as escaping but somehow the compiler always gives an error.

The error i get is

Closure use of non-escaping parameter 'completion' may allow it to escape.

I have also mentioned the places where i get the error.

Following is the code where closure is defined.

final internal class AnimationTemplate {

var  template: ((CompletionFunc) -> AnimationFunc)

init(template:  @escaping (CompletionFunc) -> AnimationFunc)
{
    self.template = template
}

func perform(with completion: CompletionFunc) { template(completion)() }
}

internal typealias CompletionFunc =  (( Bool) -> Void)

internal typealias AnimationFunc = (() -> Void)

Now it is used here.

AnimationQueue.shared.enqueue(animation: AnimationTemplate { completion in

  //Error here
  //Closure use of non-escaping parameter 'completion' may allow it to escape
  return {

     (0 ..< self.placeholderViews.count).forEach {

      let current: PasscodeSignPlaceholderView = self.placeholderViews[$0]

      let state: PasscodeSignPlaceholderView.State = $0 < inputLength ? .active : .inactive

      //Error here
      //Closure use of non-escaping parameter 'completion' may allow it to escape
      current.setState(to: state, with: completion)
    }
  }
})

I have seen a lot of other questions regarding this error issue but none seems to solve my problem.Any help will be highly appreciated.Thanks

@dahiya_boy specified the error.Please see the updated question. — Muhammad Zohaib Ehsan, Jan 04 '18 at 10:21
Try these [1](https://stackoverflow.com/questions/38990882/closure-use-of-non-escaping-parameter-may-allow-it-to-escape) , [2](https://stackoverflow.com/questions/42214840/swift-3-closure-use-of-non-escaping-parameter-may-allow-it-to-escape/42214878) — dahiya_boy, Jan 04 '18 at 10:26
@dahiya_boy I have seen all these answers but it does not solve the issue.I have specified escaping where possible but it always gives me this error. — Muhammad Zohaib Ehsan, Jan 04 '18 at 10:27
Change this `@escaping (CompletionFunc) -> AnimationFunc` with `@escaping (CompletionFunc) -> Void` and try. — dahiya_boy, Jan 04 '18 at 10:30
@dahiya_boy I tried using Void but the requirement does not allow me to use it.It takes a closure and returns a closure. — Muhammad Zohaib Ehsan, Jan 04 '18 at 10:37
It is not neccesary, pleaase show me more code how and where you using this closure, bcz Im not getting your code properly. — dahiya_boy, Jan 04 '18 at 10:47
I have shared almost the complete code.The signature os setState and the necessary places where the code is defined and used. @dahiya_boy — Muhammad Zohaib Ehsan, Jan 04 '18 at 10:56
I'm trying to reproduce your code with stubs, but I don't really get your architecture. Why do you return AnimationFunc from CompletionFunc? How difficult at this point to reconsider your architecture and slightly rewrite the part of your app that uses this code? — Fyodor Volchyok, Jan 04 '18 at 10:59
@FyodorVolchyok the thing is I did not write the original code.I have converted the whole project from swift2 to swift3.I really don't want to rewrite this module.Hope you understands. — Muhammad Zohaib Ehsan, Jan 04 '18 at 11:03

score 0 · Accepted Answer · answered Jan 05 '18 at 09:30

Making the closure optional solved the issue.It was an eventual hit and trial.

 internal typealias CompletionFunc =  (( Bool) -> Void)?

I saw this closure was passed to a function which accepts an optional closure.Then I decided to make it optional.When i made it optional the error was gone. And xcode was giving me a wrong error perhaps.

Escaping closure swift3

1 Answers1