How can I make UIScrollView/UIPageControl infinite? - ios

Question

I have created a simple image scrolling with UIPageControl and UIScrollView, I have three pages ! so what I need is when user scrolls page 0 to left , actually scroll should move to the page 3 and vice versa . I have checked Apple sample code but it was so complicated !, here is my codes :
- (void)setupScrollView {
_pageControl.currentPage = 0;
_pageControl.numberOfPages = 3;
[_scrollView setContentSize:CGSizeMake(_scrollView.frame.size.width * _pageControl.numberOfPages, _scrollView.frame.size.height)];
_scrollView.delegate = self;
[self createPageWithImage:_image1 forPage:0];
[self createPageWithImage:_image2 forPage:1];
[self createPageWithImage:_image3 forPage:2];
}
- (void)createPageWithImage:(UIImageView *)frameImage forPage:(int)page
{
UIView *newView = [[UIView alloc] initWithFrame: CGRectMake(_scrollView.frame.size.width * page, 0, _scrollView.frame.size.width, _scrollView.frame.size.height)];
[newView addSubview: frameImage];
[_scrollView addSubview: newView];
}
- (void)scrollViewDidScroll: (UIScrollView *) sView
{
CGFloat offset = _scrollView.contentOffset.x;
CGFloat pageSize = _scrollView.frame.size.width;
int page = floor((offset + (pageSize/2)) / pageSize);
_pageControl.currentPage = page;
}
- (IBAction)changeThePage
{
CGRect pageRect = CGRectMake(_pageControl.currentPage * _scrollView.frame.size.width, 0, _scrollView.frame.size.width, _scrollView.frame.size.height);
[_scrollView scrollRectToVisible: pageRect animated: YES];
}

Answer 1

Adding the methods which I have changed. I have commented wherever necessary.
- (void)setupScrollView {
_pageControl.currentPage = 0;
_pageControl.numberOfPages = 3 ;
//Add 2 more pages.
[_scrollView setContentSize:CGSizeMake(_scrollView.frame.size.width * (_pageControl.numberOfPages + 2), _scrollView.frame.size.height)];
_scrollView.delegate = self;
// Seriously recommend this for this type of apps.
_scrollView.pagingEnabled = YES;
// Do not instantiate imageviews. Send only image names as string.
// Add last image at beginning of scroll view.
[self createPageWithImageName:#"imageName3" forPage:0];
// Increase page number of existing images.
[self createPageWithImageName:#"imageName1" forPage:1];
[self createPageWithImageName:#"imageName2" forPage:2];
[self createPageWithImageName:#"imageName3" forPage:3];
//Add first image at end of scroll view
[self createPageWithImageName:#"imageName1" forPage:4];
// Show first image but present in second page.
[_scrollView setContentOffset:CGPointMake(_scrollView.frame.size.width, 0) animated:NO];
}
// Instead of sending image views, send image name. Create image view inside this method.
// This is because, since we are adding two more images, separate image view needs
// to be created. Otherwise, same image view will be used and one added at the end
// will be used as the frame of the image.
- (void)createPageWithImageName:(NSString *)imageName forPage:(int)page
{
UIView *newView = [[UIView alloc] initWithFrame: CGRectMake(_scrollView.frame.size.width * page, 0, _scrollView.frame.size.width, _scrollView.frame.size.height)];
UIImageView *imageView = [[UIImageView alloc] initWithFrame:newView.bounds];
imageView.image = [UIImage imageNamed:imageName];
[newView addSubview: imageView];
[_scrollView addSubview: newView];
}
- (void)scrollViewDidScroll: (UIScrollView *) sView
{
CGFloat offset = _scrollView.contentOffset.x;
CGFloat pageSize = _scrollView.frame.size.width;
int page = floor((offset + (pageSize/2)) / pageSize);
if (page == 0) {
page = _pageControl.numberOfPages - 1;
}
else if (page == _pageControl.numberOfPages + 1) {
page = 0;
}
else {
page = page - 1;
}
_pageControl.currentPage = page;
// If present in scroll view's first page, move it to second last page
if (offset < pageSize) {
[_scrollView setContentOffset:CGPointMake(pageSize * 3 + offset, 0) animated:NO];
}
// If present in scroll view's last page, move it to second page.
else if (offset >= pageSize * (_pageControl.numberOfPages + 1)) {
CGFloat difference = offset - pageSize * _pageControl.numberOfPages;
[_scrollView setContentOffset:CGPointMake(difference, 0) animated:NO];
}
}
The method of changeThePage is not needed for this code.
Hope this answer helps you.