Swift - Implement global activity indicator

Question

I'm currently attempting to make a global activity indicator in swift, which is called whenever a fetch to the api is made. The idea is that the activity indicator will appear in the top left of a navigation bar (navigation view controller's child), and is available on every app page.

Can't show example image due to new account / low rep

I have the activity indicator displaying correctly, I'm just not sure on how to make it available from any page on the app - i've considered an extension, but am not sure on what the best way to approach it is. Any help would be greatly appreciated.

Activity Indicator Code:

let activityIndicator: UIActivityIndicatorView = UIActivityIndicatorView(activityIndicatorStyle: UIActivityIndicatorViewStyle.White)
var activityItem = UIBarButtonItem()

func navBarActivity() {
    // Call navBarActivity() to start activity indicator
    // Use navigationItem.leftBarButtonItem = nil to stop activity indicator
    activityIndicator.startAnimating()
    activityIndicator.hidden = false

    self.activityItem = UIBarButtonItem(customView: activityIndicator)
    self.navigationItem.leftBarButtonItem = activityItem
}

Answer 1

I would recommend extension like this.

extension UIViewController {
    func displayNavBarActivity() {
        let indicator = UIActivityIndicatorView(activityIndicatorStyle: .White)
        indicator.startAnimating()
        let item = UIBarButtonItem(customView: indicator)

        self.navigationItem.leftBarButtonItem = item
    }

    func dismissNavBarActivity() {
        self.navigationItem.leftBarButtonItem = nil
    }
}

Call self.displayNavBarActivity() before api call, and call self.dismissNavBarActivity() after api call done.

However, I want you to check networkActivityIndicatorVisible of UIApplication. Consider using this option.

Specify YES if the app should show network activity and NO if it should not. The default value is NO. A spinning indicator in the status bar shows network activity. The app may explicitly hide or show this indicator.

https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIApplication_Class/#//apple_ref/occ/instp/UIApplication/networkActivityIndicatorVisible