Nsinternalinconsistencyexception', Reason: 'No Uicollectionviewlayoutattributes Instance for -Layoutattributesforitematindexpath, Custom Layout

NSInternalInconsistencyException', reason: 'no UICollectionViewLayoutAttributes instance for -layoutAttributesForItemAtIndexPath, custom layout

For those who encounter the same issue, I discovered that when you do

self.collectionView?.performBatchUpdates({ () -> Void in
        // add new items into collection
        self.collectionView?.insertItemsAtIndexPaths(indexPaths)

        }, completion: { (finished) -> Void in
            // do insertion animations
    });

the layoutAttributesForElementsInRect method is not called and the layoutAttributesForItemAtIndexPathis called instead.

Therefore, you must also override layoutAttributesForItemAtIndexPath in the custom layout like so:

override func layoutAttributesForItemAtIndexPath(indexPath: NSIndexPath) -> UICollectionViewLayoutAttributes? {

    // Logic that calculates the UICollectionViewLayoutAttributes of the item
    // and returns the UICollectionViewLayoutAttributes
    return self.singleItemLayout(indexPath)
}

EDIT: Also, if you encounter flicker when the batch insertItemsAtIndexPaths method on it's own.

Why does my custom UICollectionViewLayout throw an error when adding space between cells?

Found the solution! Apparently overriding layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? fixes the issue! But I have no idea why.

UICollectionView exception in UICollectionViewLayoutAttributes from iOS7

You need to invalidate the existing layout before updating, see the end of the error message:

without invalidating the layout'

[collectionViewLayout invalidateLayout];

Apple Documentation for UICollectionViewLayout

Using [UICollectionView performBatchUpdates:] with a UICollectionViewFlowLayout that has UIDynamics

try

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewLayoutAttributes *layoutAttributes = [self.dynamicAnimator layoutAttributesForCellAtIndexPath:indexPath];
    if(!layoutAttributes) {
        layoutAttributes = [super layoutAttributesForItemAtIndexPath:indexPath];
    }
    return layoutAttributes;
}

when you execute performBatchUpdates, [self.dynamicAnimator layoutAttributesForCellAtIndexPath: returns nil if cell which will be created by update is not visible.
So just returns super(perhaps UICollectionViewFlowLayout)'
s layoutAttributes for now.
And when the cell about to be displayed, UIDynamicAnimator will do the job for you.

UICollectionViewLayoutAttributes custom derived class instance is not created

Need to use the generic version of CreateForCell:

UICollectionViewLayout.CreateForCell<CustomLayoutAttributes>(indexPath);

This is because C# doesn't have virtual class methods like Objective-C does so it can't tell in CreateForCell which class you called it on unless you tell it with a type argument.

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