Question

I’m using altered sample code from PhotoScroller within my app. I have a table view of image thumbnails, and I can pass the array of images that populate that table to PhotoViewController. Currently, PhotoViewController starts with the first image in my array and I can scroll back and forth. This works properly as Apple’s sample code.

Now What I want to do is tap a table cell with thumbnail, and start scrolling images beginning with the image in my array at that index. Ex: if I have 5 images in a table and I tap image #3, I want the first image in PhotoViewController to be that third image, and able to scroll left or right to #2 or #4. Hope this makes sense.

I see in PhotoViewController that sub views are being added per image. Any way I can tell it “jump to view #3” without destroying the other views or their overall order of appearance? Any ideas or advice is welcome. Code can be found on the iOS developer site for PhotoScroller sample code.

Ok, I’m rambling… Thanks in advance for your help!

Answer 1

The way I do this is to have a variable called startingPage which gets set in the initialiser of the photo view controller. Then when the pages are being created, first set the correct offset for the scroll view.

So in the PhotoScroller case that would be in loadView. Like so:

- (void)loadView 
{
    // Step 1: make the outer paging scroll view
    CGRect pagingScrollViewFrame = [self frameForPagingScrollView];
    pagingScrollView = [[UIScrollView alloc] initWithFrame:pagingScrollViewFrame];
    pagingScrollView.pagingEnabled = YES;
    pagingScrollView.backgroundColor = [UIColor blackColor];
    pagingScrollView.showsVerticalScrollIndicator = NO;
    pagingScrollView.showsHorizontalScrollIndicator = NO;
    pagingScrollView.contentSize = [self contentSizeForPagingScrollView];
    pagingScrollView.delegate = self;
    self.view = pagingScrollView;

    // Set the content offset of the scrollview
    CGRect bounds = pagingScrollView.bounds;
    CGPoint contentOffset = CGPointMake(bounds.size.width * startingPage, 0.0f);
    [pagingScrollView setContentOffset:contentOffset animated:NO];

    // Step 2: prepare to tile content
    recycledPages = [[NSMutableSet alloc] init];
    visiblePages  = [[NSMutableSet alloc] init];
    [self tilePages];
}