Display activity indicator on api call Swift

Question

I want to display an activity indicator when api call is performed. The activity indicator should stop when the api response is received

But Activity indicator is not displaying during the api call am new to swift here is my code.

import UIKit

var ARR_states : NSArray = NSArray()
var activityIndicatorView: UIActivityIndicatorView = UIActivityIndicatorView()
var VW_overlay: UIView = UIView()

class VC_search_Course: UIViewController {

@IBOutlet weak var TBL_states :UITableView!

override func viewDidLoad() {
    super.viewDidLoad()

    VW_overlay = UIView(frame: UIScreen.main.bounds)
    VW_overlay.backgroundColor = UIColor(red: 0, green: 0, blue: 0, alpha: 0.5)

    activityIndicatorView = UIActivityIndicatorView(activityIndicatorStyle: .whiteLarge)
    activityIndicatorView.frame = CGRect(x: 0, y: 0, width: activityIndicatorView.bounds.size.width, height: activityIndicatorView.bounds.size.height)

    activityIndicatorView.center = VW_overlay.center
    VW_overlay.addSubview(activityIndicatorView)
    VW_overlay.center = view.center
    view.addSubview(VW_overlay)

    activityIndicatorView.startAnimating()
    perform(#selector(self.Places_API), with: activityIndicatorView, afterDelay: 0.01)

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}



@IBAction func button_back(sender: UIButton) {
    self.dismiss(animated: false, completion: nil)
}

func Places_API()
{
    let STR_url = String(format: "%@/search_by_location", SERVER_URL)
    let auth_tok = String(format:"%@",UserDefaults.standard.value(forKey:"auth_token") as! CVarArg)
       if let url = NSURL(string:STR_url) {
        let request = NSMutableURLRequest(url: url as URL)
        request.httpMethod = "GET"
        request.addValue("application/json", forHTTPHeaderField: "Accept")
        request.addValue(auth_tok, forHTTPHeaderField: "auth_token")

        let task = URLSession.shared.dataTask(with: request as URLRequest) {
            data, response, error in
            if error != nil {
                print("\(String(describing: error))")
                return
            }

            let temp_dictin: [AnyHashable: Any]? = ((try? JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.mutableContainers)) as? [AnyHashable: Any])


            ARR_states = temp_dictin?["course_locations"] as! NSArray
            NSLog("States response %@", ARR_states)

        }
        task.resume()
    }

    activityIndicatorView.stopAnimating()
    VW_overlay.isHidden = true
}
}

This above code is not displaying activity indicator I tried changing the view background colour. and activity indicator colour but no use

Answer 1

remove your code from

task.resume()
}

// activityIndicatorView.stopAnimating()
// VW_overlay.isHidden = true

and add into inside the block call your code in the following place

 let task = URLSession.shared.dataTask(with: request as URLRequest) {
        data, response, error in

       // call here 
       activityIndicatorView.stopAnimating()
        VW_overlay.isHidden = true


        if error != nil {
            print("\(String(describing: error))")
            return
        }
       ......