Tabbarcontroller based app using UIPagecontrol - Crashes - ios

Question

I have tab bar based app which works great. But I am wanting to use the UIPagecontrol to allow the user to swipe between views.
I have been using the tutorial http://www.samsurge.com/p/blog-page.html to achieve this for my app. But the difference between the tutorial and my app is that my app is based in tab bar system.
The UIscrollview is based on the first tab option with the class pageViewController and the connecting sub views are in IntroViewController.
The storyboard layout looks like this.
http://threepointdesign.co.uk/img2.png
The error generating is
Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayI objectAtIndex:]: index 0 beyond bounds for empty array'
Headers for both classes
#import <UIKit/UIKit.h>
#interface simpleMain : UIViewController <UIScrollViewDelegate>
#property (nonatomic, strong) IBOutlet UIScrollView *scrollView;
#property (nonatomic, strong) IBOutlet UIPageControl *pageControl;
- (IBAction)changePage:(id)sender;
#end
#import "simpleMain.h"
#interface simpleMain ()
#property (assign) BOOL pageControlUsed;
#property (assign) NSUInteger page;
#property (assign) BOOL rotating;
- (void)loadScrollViewWithPage:(int)page;
#end
#implementation simpleMain
#synthesize scrollView;
#synthesize pageControl;
#synthesize pageControlUsed = _pageControlUsed;
#synthesize page = _page;
#synthesize rotating = _rotating;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self.scrollView setPagingEnabled:YES];
[self.scrollView setScrollEnabled:YES];
[self.scrollView setShowsHorizontalScrollIndicator:NO];
[self.scrollView setShowsVerticalScrollIndicator:NO];
[self.scrollView setDelegate:self];
}
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
for (NSUInteger i =0; i < [self.childViewControllers count]; i++) {
[self loadScrollViewWithPage:i];
}
self.pageControl.currentPage = 0;
_page = 0;
[self.pageControl setNumberOfPages:[self.childViewControllers count]];
UIViewController *viewController = [self.childViewControllers objectAtIndex:self.pageControl.currentPage];
if (viewController.view.superview != nil) {
[viewController viewWillAppear:animated];
}
self.scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * [self.childViewControllers count], scrollView.frame.size.height);
}
- (void)loadScrollViewWithPage:(int)page {
if (page < 0)
return;
if (page >= [self.childViewControllers count])
return;
// replace the placeholder if necessary
UIViewController *controller = [self.childViewControllers objectAtIndex:page];
if (controller == nil) {
return;
}
// add the controller's view to the scroll view
if (controller.view.superview == nil) {
CGRect frame = self.scrollView.frame;
frame.origin.x = frame.size.width * page;
frame.origin.y = 0;
controller.view.frame = frame;
[self.scrollView addSubview:controller.view];
}
}
// At the begin of scroll dragging, reset the boolean used when scrolls originate from the UIPageControl
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
_pageControlUsed = NO;
}
// At the end of scroll animation, reset the boolean used when scrolls originate from the UIPageControl
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
_pageControlUsed = NO;
}
#end
#import "simpleMain.h"
#interface miniViewController : simpleMain {
}
#property (strong, nonatomic) IBOutlet UIView *View1;
#property (strong, nonatomic) IBOutlet UIView *View2;
#property (strong, nonatomic) IBOutlet UIView *View3;
#end
#import "MiniViewController.h"
#interface miniViewController ()
#end
#implementation miniViewController
#synthesize View1;
#synthesize View2;
#synthesize View3;
- (void)viewDidLoad
{
// Do any additional setup after loading the view, typically from a nib.
[super viewDidLoad];
[self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:#"View1"]];
[self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:#"View2"]];
[self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:#"View3"]];
}
#end
(I know the error reads, I am trying to find an element inside and empty array. I just don't know where the array is coming from and what connection it has to this setup).
Any help would be great.

Answer 1

From what I see in your storyboard and in your code, the pageViewController doesn't have any childViewControllers when the viewWillAppear is called. So that's causing the crash.

Answer 2

Ditched this tutorial as I found it had to many flaws. Problem solved.