Several Questions about ScrollView with PageControl - ios

Question

I am pretty new to iOS development and I stumbled upon several issues for which I couldn't easily find any answers yet:
General Setup: I'm using a ScrollView with PageControl inside a TabBarApplication
Is it possible to have the PageControl within the same area as the content of the pages? For me it always gets hidden by the SrollView's Views, but due to display space being rare I really need it on the same height as the actual content.
I've fooled around in some Sandbox-Project and whenever I first started to implement a button into the View of a ScrollView-Page the Pages of the ScrollView wouldn't show immediately anymore, but only after the first scroll attempt. I'd post some code about that but its basically only autogenerated from IB.
This is a general Question about possibilities again: The main design of the Project should be a TabBarApplication with a NavigationController letting you go deeper into sub-menues like it is pretty common. Now in one of the Tabs there should be the PageControl, in which you can then again go into sub-menues by pushing Views on a NavigationController stack . Is this possible?
Some Code for 2.
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
NSMutableArray *controllers = [[NSMutableArray alloc] init];
for (unsigned i = 0; i < kNumberOfPages; i++) {
[controllers addObject:[NSNull null]]; // [TaskPageViewController new]];
}
self.viewControllers = controllers;
[controllers release];
// 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;
}
- (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;
}
- (void)loadScrollViewWithPage:(int)page {
if (page < 0) return;
if (page >= kNumberOfPages) return;
// replace the placeholder if necessary
TaskPageViewController *controller = [viewControllers objectAtIndex:page];
if ((NSNull *)controller == [NSNull null]) {
controller = [[TaskPageViewController alloc] init]; //WithPageNumber:page];
[viewControllers replaceObjectAtIndex:page withObject:controller];
[controller release];
}
// add the controller's view to the scroll view
if (nil == controller.view.superview) {
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
}

Answer 1

You can have two view hierarchies for this:
Have the page control inside scrollview with origin fixed at contentOffset property
Have the page control in the superview of scrollView, but at a higher index (i.e. floating above it)
This depends on where you put the code of adding the subviews. Is it in the delegate method of scrollView? viewDidLoad? Somewhere else? Some code might help.
Not sure why you'd need to have a page control when it's a drill-down navigation. Pages are for navigating same level items.