File is not opening after Downloading has been completed iOS swift

Question

When downloading completed I'm showing the alert that download has been completed after that when user click on dismiss button in alert popup self.quickLook(url: url) func will call. But not showing the file in webView. When removing the alert code everything working fine and file opening in webView.

 func showAlerts(){
        let alertController = UIAlertController(title: "Download", message: "Download Completed", preferredStyle: .alert)
        alertController.addAction(UIAlertAction(title: "dismiss", style: .default, handler: { _ in
            self.dismiss(animated: true, completion: nil)
        }))
        alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
        self.present(alertController, animated: true, completion: nil)
        
    }
   
    @IBAction func openDoc(_ sender: UIButton) {
        if let url = URL(string: "https://ikddata.ilmkidunya.com/images/books/12th-class-chemistry-chapter-10.pdf") {
            self.loadFileAsync(url: url) { response, error in
                if error == nil {
                    self.showAlerts()
                    self.quickLook(url: url)
                }
            }
        }
    }

Check console screenshot Console screenshot see msg

Answer 1

How's your quickLook implemented? I guess it also calls present. You cannot present two things at the same time on iOS.

An option would be to quickLook after the alert is dismissed. Something like:

func showAlerts(and onDismiss: (() -> Void)? = nil) {
  let alertController = UIAlertController(title: "Download", message: "Download Completed", preferredStyle: .alert)
  alertController.addAction(UIAlertAction(title: "dismiss", style: .default, handler: { _ in
    self.dismiss(animated: true) { onDismiss?() }
  }))
  alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))

  present(alertController, animated: true, completion: nil)
}
   
@IBAction func openDoc(_ sender: UIButton) {
  if let url = URL(string: "https://ikddata.ilmkidunya.com/images/books/12th-class-chemistry-chapter-10.pdf") {
    loadFileAsync(url: url) { response, error in
      if error == nil {
        self.showAlerts { self.quickLook(url: url) }
      }
    }
  }
}

Judging from your words it's exactly what you expect.