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POUICollectionView not recognized in collectionView numberOfItemsInSection:
 

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    <p>I have a problem I can't solve for some hours now...</p> <p>I have multiple UICollectionViews with different numbers of cells and different cellsizes. The CollectionViews are created programmatically and the delegates and datasources are set.</p> <p>The collectionviews are created like this:</p> <pre><code>UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init]; [layout setScrollDirection:UICollectionViewScrollDirectionHorizontal]; collectionViewOne = [[UICollectionView alloc] initWithFrame:CGRectMake(0,0,320,150) collectionViewLayout:layout]; [collectionViewOne setTag:99]; [collectionViewOne setDataSource:self]; [collectionViewOne setDelegate:self]; [collectionViewOne registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"cell"]; [collectionViewOne setBackgroundColor:bgColor]; [collectionViewOne setShowsHorizontalScrollIndicator:NO]; [collectionViewOne setBounces:YES]; [collectionViewOne setAlwaysBounceHorizontal:YES]; [collectionViewOne setScrollEnabled:YES]; [collectionViewOne setRestorationIdentifier:@"collectionViewOne"]; [scrollView addSubview:collectionViewOne]; </code></pre> <p>My functions are like these:</p> <pre><code>- (NSInteger)collectionView:(UICollectionView*)collectionView numberOfItemsInSection:(NSInteger)section { NSLog(@"restorationIdentifier: %@", collectionView.restorationIdentifier); if (collectionView == collectionViewOne) { return 3; } else if (collectionView == collectionViewTwo) { return 4; } else { return 1; } } - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath { NSLog(@"restorationIdentifier: %@", collectionView.restorationIdentifier); if (collectionView == collectionViewOne) { return CGSizeMake(100, 150); } else if (collectionView == collectionViewTwo) { return CGSizeMake(200, 150); } else { return CGSizeMake(200, 150); } } - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath { NSLog(@"restorationIdentifier: %@", collectionView.restorationIdentifier); if (collectionView == collectionViewOne) { UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)]; imageView.image = [UIImage imageNamed:@"image.png"]; [cell addSubview:imageView]; } else if (collectionView == collectionViewTwo) { //create cell of type 2 } return cell; } </code></pre> <p>In my log I get the following output (for example):</p> <p><strong>restorationIdentifier in numberOfItemsInSection: (null) restorationIdentifier in sizeForItemAtIndexPath : (null) restorationIdentifier cellForItemAtIndexPath: collectionViewOne</strong></p> <p>collectionViewOne is the restorationIdentifier on collectionViewOne. So why is it not recognized in the first two methods?</p> <p>Ofcourse the result is that I get crashes because the cellsizes and number of cells in the different CollectionViews are not properly set. The error:</p> <pre><code>*** Assertion failure in -[UICollectionViewData validateLayoutInRect:], /SourceCache/UIKit_Sim/UIKit-2903.2/UICollectionViewData.m:341 *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UICollectionView recieved layout attributes for a cell with an index path that does not exist: &lt;NSIndexPath: 0x8c31c10&gt; {length = 2, path = 0 - 2}' </code></pre> <p>How can I fix this?</p>
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    1. COHow and where do you set `collectionViewOne` and `collectionViewTwo`? And what crash are you getting exactly?
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    2. COI set them in a method which I call in viewDidLoad. The crash I'm getting is like Assertion failure in -[UICollectionViewData validateLayoutInRect
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    3. COHard to say what's wrong without more code and the exact crash, but I don't see anything in your `cellForItemAtIndexPath` method that's handling the collection view not being one or two. Have you confirmed that `collectionViewOne` and `collectionViewTwo` are not nil in these methods?
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