Can we customize the page indicator in UIPageViewController?

You can use UIAppearance to change the color of UIPageControl. Try this in your AppDelegate’s didFinishLaunchingWithOptions function.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    UIPageControl *pageControl = [UIPageControl appearance];
    pageControl.pageIndicatorTintColor = [UIColor lightGrayColor];
    pageControl.currentPageIndicatorTintColor = [UIColor blackColor];
    pageControl.backgroundColor = [UIColor blueColor];

    return YES;
}

EDIT:

To apply style only to a particular view controller, use appearanceWhenContainedIn instead, as following:

UIPageControl *pageControl = [UIPageControl appearanceWhenContainedIn:[MyViewController class], nil];

Now, only UIPageControl objects contained in the MyViewController are going to adapt this style.

Thanks Mike & Shingoo!

EDIT:
If you see black background around UIPageControl at the bottom of your screen, it is due to the background color of your UIPageViewController not UIPageControl. You can change this color as following:

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor blueColor]; //Set it to whatever you like
}