RestFul Services are loading very slow in ios swift

I have Implemented an iOS Food Delivery App Using swift Language on Native iOS Platform. Its Working fine.But My Question is when I compared to my iOS app with Android App in real Devices, the server data loading very fastly in Android App. Both are using same restful Services.but I don't know, why iOS App data is loading very slowly.Can anyone guide me to solve this problem?? [Note: Both iPhone and Android Devices running on same Wi-Fi Network]

After Successful getting of data from Server I am using this code

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    if (rows == nil) {
        myTable.separatorStyle = .none

        activityIndicatorView.startAnimating()

        dispatchQueue.async {
            Thread.sleep(forTimeInterval: 3)

            OperationQueue.main.addOperation() {
                self.myTable.separatorStyle = .singleLine

                self.activityIndicatorView.stopAnimating()


                //self.rows = ["One", "Two", "Three", "Four", "Five"]

                //self.myTable.reloadData()
            }
        }
    }
}

viewdidload()

{ activityIndicatorView = UIActivityIndicatorView(activityIndicatorStyle: .gray)

    myTable.backgroundView = activityIndicatorView

}