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PONeed help for pushing a view in UIScrollView / UIPageControl on storyboard
 

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  1. PONeed help for pushing a view in UIScrollView / UIPageControl on storyboard
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    <p>I'm trying to implement UIScrollView with UIPageControl on storyboard to display multiple views. All the examples, tutorials or informations I found are using xib and not storyboard. I tried to adapt Apple's sample code but I'm missing something. As you can see, it is quite simple.</p> <p><img src="https://i.stack.imgur.com/JWQgL.png" alt="enter image description here"></p> <p>However, either I get an error in ContentController.m <strong><em>-[NSNull view]: unrecognized selector sent to instance 0x129acd8</em></strong> when I test <strong><em>if (controller.view.superview == nil)</em></strong> where I push the view (see below after the first half of code).</p> <p>Or only the UIScrollView and UIPageControl are working and I am not able to push the view in the UIScrollView:</p> <p><img src="https://i.stack.imgur.com/MAK8m.png" alt="enter image description here"></p> <p>I know it's a simple question, however I spent many hours on this and any help will be appreciated.</p> <p>I post the full code as it may help someone when resolved like a kind of tutorial. I will correct the code if/when needed according to contributions.</p> <p>Thanks in advance</p> <p><strong>AppDelegate.h</strong></p> <pre><code>// Nothing special as I don't want to manage it through application delegate @interface AppDelegate : UIResponder &lt;UIApplicationDelegate&gt; @property (strong, nonatomic) UIWindow *window; @end </code></pre> <p><strong>AppDelegate.m</strong></p> <pre><code>// Nothing special as I don't want to manage it through application delegate #import "AppDelegate.h" @implementation AppDelegate @synthesize window = _window; - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { return YES; } - (void)applicationWillResignActive:(UIApplication *)application { } - (void)applicationDidEnterBackground:(UIApplication *)application { } - (void)applicationWillEnterForeground:(UIApplication *)application { } - (void)applicationDidBecomeActive:(UIApplication *)application { } - (void)applicationWillTerminate:(UIApplication *)application { } @end </code></pre> <p><strong>ContentController.h</strong></p> <pre><code>// From Apple's PageControl sample code #import &lt;UIKit/UIKit.h&gt; @interface ContentController : UIViewController &lt;UIScrollViewDelegate&gt; { UIScrollView *scrollView; UIPageControl *pageControl; NSMutableArray *viewControllers; BOOL pageControlUsed; } @property (nonatomic, retain) IBOutlet UIScrollView *scrollView; @property (nonatomic, retain) IBOutlet UIPageControl *pageControl; @property (nonatomic, retain) NSMutableArray *viewControllers; - (IBAction)changePage:(id)sender; @end </code></pre> <p><strong>ContentController.m</strong></p> <pre><code>// From Apple's PageControl sample code #import "AppDelegate.h" #import "ContentController.h" #import "MyViewController.h" // Private methods @interface ContentController (PrivateMethods) - (void)loadScrollViewWithPage:(int)page; - (void)scrollViewDidScroll:(UIScrollView *)sender; @end @implementation ContentController @synthesize scrollView, pageControl, viewControllers; static NSUInteger kNumberOfPages = 6; - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. self.navigationController.navigationBar.hidden=YES; // view controllers are created lazily in the meantime, load the array with // placeholders which will be replaced on demand NSMutableArray *controllers = [[NSMutableArray alloc] init]; for (unsigned i = 0; i &lt; kNumberOfPages; i++) { [controllers addObject:[NSNull null]]; } self.viewControllers = controllers; // a page is the width of the scroll view scrollView.pagingEnabled = YES; scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * kNumberOfPages, scrollView.frame.size.height); scrollView.showsHorizontalScrollIndicator = NO; scrollView.showsVerticalScrollIndicator = NO; scrollView.scrollsToTop = NO; scrollView.delegate = self; pageControl.numberOfPages = kNumberOfPages; pageControl.currentPage = 0; // pages are created on demand // load the visible page // load the page on either side to avoid flashes when the user starts scrolling [self loadScrollViewWithPage:0]; [self loadScrollViewWithPage:1]; } - (void)viewDidUnload { [super viewDidUnload]; // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; self.pageControl=nil; self.pageControl = nil; self.viewControllers = nil; } - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; } - (void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; } - (void)viewWillDisappear:(BOOL)animated { [super viewWillDisappear:animated]; } - (void)viewDidDisappear:(BOOL)animated { [super viewDidDisappear:animated]; } - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown); } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)loadScrollViewWithPage:(int)page { if (page &lt; 0) return; if (page &gt;= kNumberOfPages) return; // replace the placeholder if necessary MyViewController *controller = [viewControllers objectAtIndex:page]; if ((NSNull *)controller == [NSNull null]) // &lt;== *** HERE SEEMS TO BE THE ERROR *** { controller = [[MyViewController alloc] initWithPageNumber:page initWithNibName:nil bundle:nil]; [viewControllers replaceObjectAtIndex:page withObject:controller]; } // add the controller's view to the scroll view if (controller.view.superview == nil) { CGRect frame = scrollView.frame; frame.origin.x = frame.size.width * page; frame.origin.y = 0; controller.view.frame = frame; [scrollView addSubview:controller.view]; } } - (void)scrollViewDidScroll:(UIScrollView *)sender { // We don't want a "feedback loop" between the UIPageControl and the scroll delegate in // which a scroll event generated from the user hitting the page control triggers updates from // the delegate method. We use a boolean to disable the delegate logic when the page control is used. if (pageControlUsed) { // do nothing - the scroll was initiated from the page control, not the user dragging return; } // Switch the indicator when more than 50% of the previous/next page is visible CGFloat pageWidth = scrollView.frame.size.width; int page = floor((scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1; pageControl.currentPage = page; // load the visible page and the page on either side of it (to avoid flashes when the user starts scrolling) [self loadScrollViewWithPage:page - 1]; [self loadScrollViewWithPage:page]; [self loadScrollViewWithPage:page + 1]; // A possible optimization would be to unload the views+controllers which are no longer visible } // At the begin of scroll dragging, reset the boolean used when scrolls originate from the UIPageControl - (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView { pageControlUsed = NO; } - (IBAction)changePage:(id)sender { int page = pageControl.currentPage; // load the visible page and the page on either side of it (to avoid flashes when the user starts scrolling) [self loadScrollViewWithPage:page - 1]; [self loadScrollViewWithPage:page]; [self loadScrollViewWithPage:page + 1]; // update the scroll view to the appropriate page CGRect frame = scrollView.frame; frame.origin.x = frame.size.width * page; frame.origin.y = 0; [scrollView scrollRectToVisible:frame animated:YES]; // Set the boolean used when scrolls originate from the UIPageControl. See scrollViewDidScroll: above. pageControlUsed = YES; } @end </code></pre> <p><strong>MyViewController.h</strong></p> <pre><code>#import &lt;UIKit/UIKit.h&gt; @interface MyViewController : UIViewController { UILabel *pageNumberLabel; int pageNumber; } @property (nonatomic, retain) IBOutlet UILabel *pageNumberLabel; - (id)initWithPageNumber:(int)page initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil; @end </code></pre> <p><strong>MyViewController.m</strong></p> <pre><code>#import "MyViewController.h" @implementation MyViewController @synthesize pageNumberLabel; - (void)loadView { } - (void)viewDidLoad { [super viewDidLoad]; // Set the label and background color when the view has finished loading pageNumberLabel.text = [NSString stringWithFormat:@"Page %d", pageNumber + 1]; } - (void)viewDidUnload { [super viewDidUnload]; // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationPortrait); } // Load the view nib and initialize the pageNumber ivar // classic initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil // class adapted to init the page number // /!\ be careful, I'm not sure it's working properly - (id)initWithPageNumber:(int)page initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { pageNumber = page; NSLog(@"pageNumber = %i", pageNumber); } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } @end </code></pre>
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      1. PONeed help for pushing a view in UIScrollView / UIPageControl on storyboard
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    1. COIf anyone knows a link to a tutorial **using storyboard** I'll appreciate.
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      1. PONeed help for pushing a view in UIScrollView / UIPageControl on storyboard
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    2. COHere is a good tutorial : http://www.raywenderlich.com/10518/how-to-use-uiscrollview-to-scroll-and-zoom-content
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