As described in this UICollectionViewFlowlayout, Step 1:
// Need to overflow our actual visible rect slightly to avoid flickering.
var visibleRect = CGRectInset(self.collectionView!.bounds, -100, -100)
var itemsInVisibleRectArray: NSArray = super.layoutAttributesForElementsInRect(visibleRect)!
var itemsIndexPathsInVisibleRectSet: NSSet = NSSet(array: itemsInVisibleRectArray.valueForKey("indexPath") as [AnyObject])
// Step 1: Remove any behaviours that are no longer visible.
var noLongerVisibleBehaviours = (self.dynamicAnimator.behaviors as NSArray).filteredArrayUsingPredicate(NSPredicate(block: {behaviour, bindings in
var currentlyVisible: Bool = itemsIndexPathsInVisibleRectSet.member((behaviour as UIAttachmentBehavior).items.first!.indexPath) != nil
return !currentlyVisible
}))
"Type of expression is ambiguous without more context" .. what should I do? I am really stuck :/
Thank you for any help I can get on this...
If anyone might just want to solve this problem, look here:
let visibleRect = CGRectInset(self.collectionView!.bounds, -100, -100)
let itemsInVisibleRect = super.layoutAttributesForElementsInRect(visibleRect)!
let indexPathsInVisibleRect = Set(itemsInVisibleRect.map({ (attribute) -> NSIndexPath in
return attribute.indexPath
}))
// Step 1: Remove any behaviours that are no longer visible.
let noLongerVisisbleBehaviors = self.dynamicAnimator.behaviors.filter { (eachBehavior) -> Bool in
var currentlyVisible = false
if let behavior = eachBehavior as? UIAttachmentBehavior, first = behavior.items.first as? UICollectionViewLayoutAttributes {
currentlyVisible = indexPathsInVisibleRect.contains(first.indexPath)
}
return !currentlyVisible
}
Thankfully, this has proven to be a truly a huge save for the day :}