4
我已經實現了自定義FlowLayout子，這顯然已經排除我經由storyboard加入headerView（複選框消失）時加入HeaderView到的CollectionView。有沒有其他的方法可以使用storyboards？使用自定義的FlowLayout（SWIFT）
有關於如何添加headerView編程一些答案，但他們在objective-C，我怎麼可以添加一個使用Swift？
以下不會產生頭部看法，我想不通爲什麼？
CollectionViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Setup Header
self.collectionView!.registerClass(PinHeaderView.self, forSupplementaryViewOfKind:UICollectionElementKindSectionHeader, withReuseIdentifier: headerIdentifier)
}
override func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
//1
switch kind {
//2
case UICollectionElementKindSectionHeader:
//3
let headerView = collectionView.dequeueReusableSupplementaryViewOfKind(kind,withReuseIdentifier: "PinHeaderView",
forIndexPath: indexPath)
as! PinHeaderView
headerView.pinHeaderLabel.text = boardName
return headerView
default:
//4
fatalError("Unexpected element kind")
}
}
}
class PinHeaderView: UICollectionReusableView {
@IBOutlet weak var pinHeaderLabel: UILabel!
}
我的佈局類：
import UIKit
protocol PinterestLayoutDelegate {
// 1. Method to ask the delegate for the height of the image
func collectionView(collectionView:UICollectionView, heightForPhotoAtIndexPath indexPath:NSIndexPath , withWidth:CGFloat) -> CGFloat
// 2. Method to ask the delegate for the height of the annotation text
func collectionView(collectionView: UICollectionView, heightForAnnotationAtIndexPath indexPath: NSIndexPath, withWidth width: CGFloat) -> CGFloat
func columnsForDevice() -> Int
}
class PinterestLayoutAttributes:UICollectionViewLayoutAttributes {
// 1. Custom attribute
var photoHeight: CGFloat = 0.0
var headerHeight: CGFloat = 0.0
// 2. Override copyWithZone to conform to NSCopying protocol
override func copyWithZone(zone: NSZone) -> AnyObject {
let copy = super.copyWithZone(zone) as! PinterestLayoutAttributes
copy.photoHeight = photoHeight
return copy
}
// 3. Override isEqual
override func isEqual(object: AnyObject?) -> Bool {
if let attributtes = object as? PinterestLayoutAttributes {
if(attributtes.photoHeight == photoHeight ) {
return super.isEqual(object)
}
}
return false
}
}
class PinterestLayout: UICollectionViewLayout {
//1. Pinterest Layout Delegate
var delegate:PinterestLayoutDelegate!
//2. Configurable properties
//moved numberOfColumns
var cellPadding: CGFloat = 6.0
//3. Array to keep a cache of attributes.
private var cache = [PinterestLayoutAttributes]()
//4. Content height and size
private var contentHeight:CGFloat = 0.0
private var contentWidth: CGFloat {
let insets = collectionView!.contentInset
return CGRectGetWidth(collectionView!.bounds) - (insets.left + insets.right)
}
override class func layoutAttributesClass() -> AnyClass {
return PinterestLayoutAttributes.self
}
override func prepareLayout() {
// 1. Only calculate once
//if cache.isEmpty {
// 2. Pre-Calculates the X Offset for every column and adds an array to increment the currently max Y Offset for each column
let numberOfColumns = delegate.columnsForDevice()
let columnWidth = contentWidth/CGFloat(numberOfColumns)
var xOffset = [CGFloat]()
for column in 0 ..< numberOfColumns {
xOffset.append(CGFloat(column) * columnWidth)
}
var column = 0
var yOffset = [CGFloat](count: numberOfColumns, repeatedValue: 0)
// 3. Iterates through the list of items in the first section
for item in 0 ..< collectionView!.numberOfItemsInSection(0) {
let indexPath = NSIndexPath(forItem: item, inSection: 0)
// 4. Asks the delegate for the height of the picture and the annotation and calculates the cell frame.
let width = columnWidth - cellPadding*2
let photoHeight = delegate.collectionView(collectionView!, heightForPhotoAtIndexPath: indexPath , withWidth:width)
let annotationHeight = delegate.collectionView(collectionView!, heightForAnnotationAtIndexPath: indexPath, withWidth: width)
let height = cellPadding + photoHeight + annotationHeight + cellPadding
let frame = CGRect(x: xOffset[column], y: yOffset[column], width: columnWidth, height: height)
let insetFrame = CGRectInset(frame, cellPadding, cellPadding)
// 5. Creates an UICollectionViewLayoutItem with the frame and add it to the cache
let attributes = PinterestLayoutAttributes(forCellWithIndexPath: indexPath)
attributes.photoHeight = photoHeight
attributes.frame = insetFrame
cache.append(attributes)
// 6. Updates the collection view content height
contentHeight = max(contentHeight, CGRectGetMaxY(frame))
yOffset[column] = yOffset[column] + height
column = column >= (numberOfColumns - 1) ? 0 : ++column
}
//}
}
override func layoutAttributesForSupplementaryViewOfKind(elementKind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionViewLayoutAttributes? {
let attributes = PinterestLayoutAttributes(forSupplementaryViewOfKind: elementKind, withIndexPath: indexPath)
attributes.headerHeight = 100.0
attributes.frame = (self.collectionView?.frame)!
return attributes
}
override func collectionViewContentSize() -> CGSize {
return CGSize(width: contentWidth, height: contentHeight)
}
override func layoutAttributesForElementsInRect(rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
var layoutAttributes = [UICollectionViewLayoutAttributes]()
// Loop through the cache and look for items in the rect
for attributes in cache {
if CGRectIntersectsRect(attributes.frame, rect) {
layoutAttributes.append(attributes)
}
}
return layoutAttributes
}
}
您是否看到過Apple的高級集合視圖示例代碼？ – Andrea
謝謝，我只是檢查了它，但它在Obj-C =（ – GarySabo