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POUIScrollView Infinite Scrolling
 

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    <p>I'm attempting to setup a scrollview with infinite (horizontal) scrolling.</p> <p>Scrolling forward is easy - I have implemented scrollViewDidScroll, and when the contentOffset gets near the end I make the scrollview contentsize bigger and add more data into the space (i'll have to deal with the crippling effect this will have later!)</p> <p>My problem is scrolling back - the plan is to see when I get near the beginning of the scroll view, then when I do make the contentsize bigger, move the existing content along, add the new data to the beginning and then - importantly adjust the contentOffset so the data under the view port stays the same.</p> <p>This works perfectly if I scroll slowly (or enable paging) but if I go fast (not even very fast!) it goes mad! Heres the code:</p> <pre><code>- (void) scrollViewDidScroll:(UIScrollView *)scrollView { float pageNumber = scrollView.contentOffset.x / 320; float pageCount = scrollView.contentSize.width / 320; if (pageNumber &gt; pageCount-4) { //Add 10 new pages to end mainScrollView.contentSize = CGSizeMake(mainScrollView.contentSize.width + 3200, mainScrollView.contentSize.height); //add new data here at (320*pageCount, 0); } //*** the problem is here - I use updatingScrollingContent to make sure its only called once (for accurate testing!) if (pageNumber &lt; 4 &amp;&amp; !updatingScrollingContent) { updatingScrollingContent = YES; mainScrollView.contentSize = CGSizeMake(mainScrollView.contentSize.width + 3200, mainScrollView.contentSize.height); mainScrollView.contentOffset = CGPointMake(mainScrollView.contentOffset.x + 3200, 0); for (UIView *view in [mainContainerView subviews]) { view.frame = CGRectMake(view.frame.origin.x+3200, view.frame.origin.y, view.frame.size.width, view.frame.size.height); } //add new data here at (0, 0); } //** MY CHECK! NSLog(@"%f", mainScrollView.contentOffset.x); } </code></pre> <p>As the scrolling happens the log reads: 1286.500000 1285.500000 1284.500000 1283.500000 1282.500000 1281.500000 1280.500000</p> <p>Then, when pageNumber&lt;4 (we're getting near the beginning): 4479.500000 4479.500000</p> <p>Great! - but the numbers should continue to go down in the 4,000s but the next log entries read: 1278.000000 1277.000000 1276.500000 1275.500000 etc....</p> <p>Continiuing from where it left off!</p> <p>Just for the record, if scrolled slowly the log reads: 1294.500000 1290.000000 1284.500000 1280.500000 4476.000000 4476.000000 4473.000000 4470.000000 4467.500000 4464.000000 4460.500000 4457.500000 etc....</p> <p>Any ideas????</p> <p>Thanks</p> <p>Ben.</p>
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