Loading multiple View controller in UIPageViewController - Swiping shows blank screen - ios

Question

I am loading multiple UIViewControllers in UIPageViewController with each UIViewController having their own navigation bar. I have implemented all the required data source and delegate methods for UIPageViewController and it showing up correctly.
But when I scroll my view controller horizontally, more often, I see a white blank screen instead of my view controller. Below is my code.
Any clue what could be wrong here.
PS: I tried by removing the IF condition in my viewControllerForRequestID method and returning a new controller every time. This works but then I end up with one view controller showing up twice in pagination.
- (UIViewController *)pageViewController:(UIPageViewController *)iPageViewController viewControllerBeforeViewController:(UIViewController *)iViewController {
[self.pageControl setCurrentPage:self.selectedRequestIndex];
if (self.selectedRequestIndex == 0) {
return nil;
}
NSUInteger aNewSelectedRequestIndex = self.selectedRequestIndex - 1;
NSString *aPreviousRequestID = [self.paginationRequestIDList[aNewSelectedRequestIndex] stringValue];
self.selectedRequestIndex = aNewSelectedRequestIndex;
self.selectedRequestID = aPreviousRequestID;
return [self viewControllerForRequestID:self.selectedRequestID];
}
- (UIViewController *)pageViewController:(UIPageViewController *)iPageViewController viewControllerAfterViewController:(UIViewController *)iViewController {
[self.pageControl setCurrentPage:self.selectedRequestIndex];
if (self.selectedRequestIndex == NSNotFound || self.selectedRequestIndex >= self.paginationRequestIDList.count - 1) {
return nil;
}
NSUInteger aNewSelectedRequestIndex = self.selectedRequestIndex + 1;
NSString *aNextRequestID = self.paginationRequestIDList[aNewSelectedRequestIndex];
self.selectedRequestIndex = aNewSelectedRequestIndex;
self.selectedRequestID = aNextRequestID;
return [self viewControllerForRequestID:self.selectedRequestID];
}
- (MyNavigationViewController *)viewControllerForRequestID:(id)iRequestID {
NSString *aRequestID = iRequestID;
// Safe check to avoid numbers in request ID
if (![iRequestID isKindOfClass:[NSString class]]) {
aRequestID = [iRequestID stringValue];
}
#synchronized (self) {
if ([self.viewControllers containsObjectForKey:iRequestID]) {
MyNavigationViewController *aNavigationController = self.viewControllers[iRequestID];
return aNavigationController;
}
MyDataModel *aRequestData = self.savedRequestData[iRequestID];
MyDataModelController *aRequestInfoController = [[MyDataModelController alloc] initWithRequestData:aRequestData];
aRequestInfoController.delegate = self;
MyNavigationViewController *aNavigationController = [[MyNavigationViewController alloc] initWithRootViewController:aRequestInfoController];
[self.viewControllers setObject:aNavigationController forKey:iRequestID];
return aNavigationController;
}
}