如何在swift中动态改变uicollectionview的大小？

Question

我想这样做：

我有子类UICollectionViewLayout，我的代码是

var horizontalInset = 0.0 as CGFloat
var verticalInset = 0.0 as CGFloat
var itemHeight = 0.0 as CGFloat
var _layoutAttributes = Dictionary<String, UICollectionViewLayoutAttributes>()
var _contentSize = CGSizeZero
var arrSize:[Int] = [0,0,0,0,0,0,1,0,0,0,0,0,1,1,1,0,0,0,0]
var random:Int?
var increaseRow = false

// MARK: -
// MARK: Layout

override func prepareLayout() {
    super.prepareLayout()

    _layoutAttributes = Dictionary<String, UICollectionViewLayoutAttributes>() // 1

    let path = NSIndexPath(forItem: 0, inSection: 0)
    let attributes = UICollectionViewLayoutAttributes(forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withIndexPath: path)

    let headerHeight = CGFloat(self.itemHeight / 4)
    attributes.frame = CGRectMake(0, 0, self.collectionView!.frame.size.width, headerHeight)

    let headerKey = layoutKeyForHeaderAtIndexPath(path)
    _layoutAttributes[headerKey] = attributes // 2

    let numberOfSections = self.collectionView!.numberOfSections() // 3

    var yOffset:CGFloat = 0.0

    for var section = 0; section < numberOfSections; section++ {

        let numberOfItems = self.collectionView!.numberOfItemsInSection(section) // 3

        var xOffset:CGFloat?

        for var item = 0; item < numberOfItems; item++ {
            let range = UInt32(19)
            random = Int(arc4random_uniform(range))
            let indexPath = NSIndexPath(forItem: item, inSection: section)
            let attributes = UICollectionViewLayoutAttributes(forCellWithIndexPath: indexPath) // 4

            var itemSize = CGSizeZero
            var increaseRow = false
                itemSize = randomItemSize() // 5

            if item == 0
            {
                xOffset = self.horizontalInset
                attributes.frame = CGRectIntegral(CGRectMake(xOffset!, yOffset, itemSize.width, itemSize.height))
                let key = layoutKeyForIndexPath(indexPath)
                _layoutAttributes[key] = attributes // 7
            }else

            {

                let previousIndexPath = NSIndexPath(forItem:indexPath.item-1, inSection:indexPath.section)
                let key = layoutKeyForIndexPath(previousIndexPath)
                let previousFrame:UICollectionViewLayoutAttributes = _layoutAttributes[key]!

                if xOffset! + previousFrame.size.width + itemSize.width > self.collectionView!.frame.size.width
                {

                    yOffset += self.horizontalInset+previousFrame.size.height

                    xOffset =  horizontalInset
                    attributes.frame = CGRectIntegral(CGRectMake(xOffset!, yOffset, itemSize.width, itemSize.height))
                    print("In if")
                    print("\n\(item):\(NSStringFromCGRect(attributes.frame))")

                    let key = layoutKeyForIndexPath(indexPath)
                    _layoutAttributes[key] = attributes // 7

                }else
                {
                    xOffset = xOffset! + horizontalInset + previousFrame.size.width
                    attributes.frame = CGRectIntegral(CGRectMake(xOffset!, yOffset, itemSize.width, itemSize.height))
                    print("In else")
                    print("\n\(item):\(NSStringFromCGRect(attributes.frame))")
                    let key = layoutKeyForIndexPath(indexPath)
                    _layoutAttributes[key] = attributes // 7
                }

            }

        }
    }

    yOffset += self.itemHeight // 10

    _contentSize = CGSizeMake(self.collectionView!.frame.size.width, yOffset + self.verticalInset) // 11

}

但获得如下输出：

你可以告诉我我错过了什么吗？我是swift的新手，也是收藏视图。我从https://github.com/bryceredd/RFQuiltLayout获得了参考，但没有得到它的代码。请帮助解决我的问题

Answer 1

设置集合视图的高度约束并在storyboard中设置一些默认值，并在类中为该约束创建一个对象。

@IBOutlet weak var collectionViewHeight: NSLayoutConstraint!

在reload（）方法之后获取集合视图的内容高度，并设置高度约束的常量值

collection_view.reloadData()

let height = collection_view.collectionViewLayout.collectionViewContentSize().height
                collectionViewHeight.constant = height
collectionViewHeight.constant = height