[英]How to dynamically change size of collection view in swift?
我想做如下:
我有 UICollectionViewLayout 的子類,我的代碼是
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
}
但得到如下輸出:
你能告訴我我錯過了什么嗎? 我是 swift 的新手,也有收藏視圖。 我從https://github.com/bryceredd/RFQuiltLayout得到了參考,但沒有得到它的代碼。 請幫助解決我的問題
設置集合視圖的高度約束並在故事板中設置一些默認值,並在您的類中為該約束創建一個對象。
@IBOutlet weak var collectionViewHeight: NSLayoutConstraint!
reload()方法后獲取collection view的內容高度並設置高度約束的常量值
collection_view.reloadData()
let height = collection_view.collectionViewLayout.collectionViewContentSize().height
collectionViewHeight.constant = height
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