Setting navigationItem.leftBarButtonItem - why does it hide my back arrow button?

When I do this :

    // --------------- SETTING NAVIGATION BAR LEFT BUTTON
    activityIndicator = [[UIActivityIndicatorView alloc] initWi开发者_开发技巧thFrame:CGRectMake(0.0,0.0,25.0,25.0)];
    [activityIndicator sizeToFit];
    activityIndicator.autoresizingMask =
    (UIViewAutoresizingFlexibleLeftMargin |
     UIViewAutoresizingFlexibleRightMargin |
     UIViewAutoresizingFlexibleTopMargin |
     UIViewAutoresizingFlexibleBottomMargin);

    UIBarButtonItem *loadingView = [[UIBarButtonItem alloc] 
                                    initWithCustomView:activityIndicator];
    //loadingView.target = self;
    self.navigationItem.leftBarButtonItem = loadingView;
    [activityIndicator startAnimating];
    // ---------------

It hides my back arrow button (the one I use to get back to the previous controller) ... why is that ?!?

How am I supposed to add my activityIndicator next to my back arrow ? (i already used titleView and rightbarbuttonitem)

---

The leftBarButtonItem is by default the back arrow. When you set it to something else, then you lose the built in back button.

If you need a custom back button with a activity indicator than you will have to provide it yourself and then when the button is pressed you need to call

[self.navigationController popViewControllerAnimated:YES];