Question

如本UICollectionViewFlowlayout所述，第1步：

// 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
}))

＆＃34;表达的类型是不明确的，没有更多的上下文＆＃34; .. 我该怎么办？我真的被卡住了：/

感谢您对我的帮助...

Answer 1

如果有人可能只是想解决这个问题，请看这里：

    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
    }

值得庆幸的是，事实证明，这对当天来说是一次真正的巨大拯救：}

表达的类型不明确SpringyCollectionViewFlowLayout

1 个答案: