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POBest way to check if UITableViewCell is completely visible
 

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  1. POBest way to check if UITableViewCell is completely visible
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    <p>I have a UITableView with cells of different heights and I need to know when they are <strong>completely</strong> visible or not.</p> <p>At the moment I am looping through each cell in the list of visible cells to check if it is completely visible every time the view is scrolled . Is this the best approach?</p> <p>Here's my code:</p> <pre><code>- (void)scrollViewDidScroll:(UIScrollView *)aScrollView { CGPoint offset = aScrollView.contentOffset; CGRect bounds = aScrollView.bounds; NSArray* cells = myTableView.visibleCells; for (MyCustomUITableViewCell* cell in cells) { if (cell.frame.origin.y &gt; offset.y &amp;&amp; cell.frame.origin.y + cell.frame.size.height &lt; offset.y + bounds.size.height) { [cell notifyCompletelyVisible]; } else { [cell notifyNotCompletelyVisible]; } } } </code></pre> <p><strong>Edit:</strong></p> <p>Please note that *- (NSArray <em>)visibleCells</em> returns visible cells which are both completely visible and partly visible.</p> <p><strong>Edit 2:</strong></p> <p>This is the revised code after combining solutions from both <em>lnafziger</em> and <em>Vadim Yelagin</em>:</p> <pre><code>- (void)scrollViewDidScroll:(UIScrollView *)aScrollView { NSArray* cells = myTableView.visibleCells; NSArray* indexPaths = myTableView.indexPathsForVisibleRows; NSUInteger cellCount = [cells count]; if (cellCount == 0) return; // Check the visibility of the first cell [self checkVisibilityOfCell:[cells objectAtIndex:0] forIndexPath:[indexPaths objectAtIndex:0]]; if (cellCount == 1) return; // Check the visibility of the last cell [self checkVisibilityOfCell:[cells lastObject] forIndexPath:[indexPaths lastObject]]; if (cellCount == 2) return; // All of the rest of the cells are visible: Loop through the 2nd through n-1 cells for (NSUInteger i = 1; i &lt; cellCount - 1; i++) [[cells objectAtIndex:i] notifyCellVisibleWithIsCompletelyVisible:YES]; } - (void)checkVisibilityOfCell:(MultiQuestionTableViewCell *)cell forIndexPath:(NSIndexPath *)indexPath { CGRect cellRect = [myTableView rectForRowAtIndexPath:indexPath]; cellRect = [myTableView convertRect:cellRect toView:myTableView.superview]; BOOL completelyVisible = CGRectContainsRect(myTableView.frame, cellRect); [cell notifyCellVisibleWithIsCompletelyVisible:completelyVisible]; } </code></pre>
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    1. COJust as a side note, you should go to all of your previous questions and accept answers of those who helped you.
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    2. COThanks for telling me! I had already given them +1 but had forgotten about the set accepted answer feature.
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    3. COYour code looks correct to me, and although it's complicated, it works. Don't fix what ain't broke, eh?
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