How to set an UIActivityIndicatorView when loading a UITableViewCell

Question

I have two UITableViewControllers, A and B. When I tap one cell in table A, I will use UINavigationController to push table view controller B. But

Answer 1

In viewDidLoad of tableview B class, add an activity indicator.

// Create the Activity Indicator.
    let activityIndicator = UIActivityIndicatorView(activityIndicatorStyle: .gray)
    activityIndicator.hidesWhenStopped = true
    view.addSubview(activityIndicator)

    // Position it at the center of the ViewController.
    activityIndicator.translatesAutoresizingMaskIntoConstraints = false
    NSLayoutConstraint.activate([
        activityIndicator.centerXAnchor.constraint(equalTo: view.centerXAnchor),
        activityIndicator.centerYAnchor.constraint(equalTo: view.centerYAnchor)])
    activityIndicator.startAnimating()

Now call your method that downloads data from the network.

myDownloadMethod()

Do it in a different thread if you don't want the UI to be non responsive during the process.

read this thread for that. Can I use a background thread to parse data?

When you are notified that the contents are downloaded, stop the indicator.

activityIndicator.stopAnimating()

Now you can call tableview.reloadData() for reloading the table to display the new contents.