UIPageViewController switch between static view controllers and keep(reuse) contents - ios

Question

I have three view controllers: Settings,Chatbox and QuickMsg.
I want to use UIPageViewController to switch between these three view controllers. For each view controller, I don't want to re-initiate the view controller between swiping pages since it contains user inputed data and I want to persist the data. I defined three view controllers as static variables.
The screen goes black when I swipe between pages. Where have I done wrong?
Thanks a lot in advance!
ChatboxController, SettingController and QuickMsgController are three UIViewController controllers.
PagingViewController.h
#import <UIKit/UIKit.h>
#import "ChatboxController.h"
#import "SettingController.h"
#import "PagingViewController.h"
#import "QuickMsgController.h"
#class ChatboxController;
#class SettingController;
#class QuickMsgController;
#interface PagingViewController : UIViewController<UIPageViewControllerDataSource>
#property (strong, nonatomic) UIPageViewController *pageController;
#property (assign, nonatomic) NSInteger index;
+(ChatboxController*) getChatboxController;
+(SettingController*) getSettingsController;
#end
PagingViewController.m
#import "PagingViewController.h"
#interface PagingViewController ()
#end
#implementation PagingViewController
static ChatboxController* chatboxViewController;
static SettingController* settingViewController;
static QuickMsgController* quickMessageViewController;
int defaultIndex=1;
NSArray *viewControllers;
+(ChatboxController*) getChatboxController
{
return chatboxViewController;
}
+(SettingController*) getSettingsController
{
return settingViewController;
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {
self.index--;
if(self.index<0)
{
self.index=0;
}
return [self viewControllerAtIndex:self.index];
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {
self.index++;
return [self viewControllerAtIndex:self.index];
}
- (UIViewController *)viewControllerAtIndex:(NSUInteger)index {
NSLog(#"index:%d",index);
if(index==1)
{
return chatboxViewController;
}
else if (index==0){
return settingViewController;
}else if(index==2)
{
NSLog(#"Quick Message");
return quickMessageViewController;
}else{
NSLog(#"error here");
return nil;
}
}
- (NSInteger)presentationCountForPageViewController:(UIPageViewController *)pageViewController {
// The number of items reflected in the page indicator.
return 3;
}
- (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController {
// The selected item reflected in the page indicator.
return defaultIndex;
}
- (void)viewDidLoad
{
[super viewDidLoad];
chatboxViewController= [self.storyboard instantiateViewControllerWithIdentifier:#"chatbox"];
settingViewController= [self.storyboard instantiateViewControllerWithIdentifier:#"settings"];
quickMessageViewController=[self.storyboard instantiateViewControllerWithIdentifier:#"quickmessages"];
self.index=defaultIndex;
// [self performSelector:#selector(loadingNextView) withObject:nil afterDelay:2.0f];
self.pageController = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStyleScroll navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:nil];
self.pageController.dataSource = self;
[[self.pageController view] setFrame:[[self view] bounds]];
NSArray *viewControllers = [NSArray arrayWithObject:chatboxViewController];
[self.pageController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];
[self addChildViewController:self.pageController];
[[self view] addSubview:[self.pageController view]];
[self.pageController didMoveToParentViewController:self];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end

Answer 1

Put your content view controllers in an NSArray:
#property (nonatomic, strong) NSArray *contentViewControllers;
Use:
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController
viewControllerBeforeViewController:(UIViewController *)viewController {
NSUInteger index = [self.contentViewControllers indexOfObject:viewController];
if (index == 0) {
return nil;
}
return self.contentViewControllers[index - 1];
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController
viewControllerAfterViewController:(UIViewController *)viewController {
NSUInteger index = [self.contentViewControllers indexOfObject:viewController];
if (index >= self.contentViewControllers.count - 1) {
return nil;
}
return self.contentViewControllers[index + 1];
}
- (NSInteger)presentationCountForPageViewController:(UIPageViewController *)pageViewController {
return self.contentViewControllers.count;
}
- (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController {
return 0;
}