static function escaping closure in Dispatch block using in VC test leak but deinit call

[cillyfly]

Hi
when I use this framework to test does function has leak. Code is like below. test unit shows it has leak, but when I use deinit to test is the viewcontroller is free, the deinit function called. and when I check memory graph, it seems no leak. can you help me to figure out why the test unit shows leak?

Function define

struct SchoolModel{ }

extension SchoolModel{
  static func loadData(completion: @escaping ([String]) -> Void){
    DispatchQueue.main.async {
      completion([])
    } 
  }
}

Using in viewcontroller

import UIKit
 
class ViewController: UIViewController {
  
  var completeData:[String] = []
  override func viewDidLoad() {
    super.viewDidLoad()
    SchoolModel.loadData { (data) in
      self.completeData = data
    }
  }
  deinit {
    print("\(#function)")
  } 
}

Test code

import Nimble
import Quick
import SpecLeaks

@testable import LeakTry

class leakTest: QuickSpec {
  override func spec() {
    describe("") {
      let test = LeakTest {
        let vc = UIStoryboard(name: "Main", bundle: Bundle.main).instantiateViewController(withIdentifier: "ViewController") as! ViewController
        return vc
      }
      describe("init") {
        it("must not leak") {
          expect(test).toNot(leak())
        }
      }
    }
  }
}

[leandromperez]

@cillyfly The problem is that the DispatchQueue.main.async is retaining the completion block (I don't know why!), and the block retains the VC.

You can see this if you put [weak self], the test will pass.
Now, why does the DispatchQueue is retaining the closure? I am not sure. Tomorrow I'll give it another try.

[cillyfly]

Thanks waiting for you ~