ScrollView with Paging

Question

I have added 3 UIViewController in my ScrollView , like this

[self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"view1"]];
[self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"view2"]];
[self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"view3"]];

How can i find which is visible ?

Answer 1

You only use - (void)addChildViewController:(UIViewController *)childController to build your own containment view controller (eg your own tabBarController), not to add a subview to a scrollview. For more information on view controller containment you should read https://developer.apple.com/library/ios/featuredarticles/ViewControllerPGforiPhoneOS/CreatingCustomContainerViewControllers/CreatingCustomContainerViewControllers.html and for a short summary you could read When to use addChildViewController vs pushViewController

If you want to add a view to a scrollview, you should simply use - (void)addSubview:(UIView *)view (eg [self.scrollView addSubview:viewOfViewControllerWithIdentifierView1] ). Also make sure you set the scrollviews contentSize and the subviews frame. However, if you want a scrollview to page between different view controllers, I'd recommend you take a look at UIPageViewController: https://developer.apple.com/library/ios/documentation/uikit/reference/UIPageViewControllerClassReferenceClassRef/UIPageViewControllerClassReference.html

Answer 2

You can check this by the calculating the contentoffset of you scroll view. For this You have to add the Delegate Methode of Scrollview.

-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{

    page_control.currentPage=scrollView.contentOffset.x/320;
}

In above code I have multiple ChildView controller having Width of 320px means complete iPhone screen width. And page_control is the Page Controller for Which I'm selecting the current Page.

Let me ask If you have any confusion.