我正在使用swift 3,并在我的应用程序中显示iPhone图库的集合视图。每一件事情都很好但我希望用户可以选择一些照片,这可能会发生但问题是我在每个单元格中使用另一个小图像,当用户选择该单元格时,图片将显示一个勾号,用户可以理解该单元格已被选中 - 这将在开始时起作用,但当用户滚动收集视图时,某些用户没有选择它们的单元格也具有此刻度! **请记住,选择和取消选择运作良好,问题只是为了显示此勾号** **我有单元格中的标记的图像,该图像将显示一个勾或没有什么时,用户选择单元格或didDeselect那**为什么集合视图中的选定单元格在UICollection View Swift 3中显示不正确?
我知道这些代码是比你想象的多,但有些人需要访问所有的代码,所以你可以看到下面
import UIKit
import Photos
class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
let arr_img = NSMutableArray()
@IBOutlet var collview: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
let allPhotosOptions : PHFetchOptions = PHFetchOptions.init()
allPhotosOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: true)]
let allPhotosResult = PHAsset.fetchAssets(with: .image, options: allPhotosOptions)
allPhotosResult.enumerateObjects({ (asset, idx, stop) in
self.arr_img.add(asset)
})
}
func getAssetThumbnail(asset: PHAsset, size: CGFloat) -> UIImage {
let retinaScale = UIScreen.main.scale
let retinaSquare = CGSize(width: size * retinaScale, height: size * retinaScale)//CGSizeMake(size * retinaScale, size * retinaScale)
let cropSizeLength = min(asset.pixelWidth, asset.pixelHeight)
let square = CGRect(x: 0, y: 0, width: cropSizeLength, height: cropSizeLength)//CGRectMake(0, 0, CGFloat(cropSizeLength), CGFloat(cropSizeLength))
let cropRect = square.applying(CGAffineTransform(scaleX: 1.0/CGFloat(asset.pixelWidth), y: 1.0/CGFloat(asset.pixelHeight)))
let manager = PHImageManager.default()
let options = PHImageRequestOptions()
var thumbnail = UIImage()
options.isSynchronous = true
options.deliveryMode = .highQualityFormat
options.resizeMode = .exact
options.normalizedCropRect = cropRect
manager.requestImage(for: asset, targetSize: retinaSquare, contentMode: .aspectFit, options: options, resultHandler: {(result, info)->Void in
thumbnail = result!
})
return thumbnail
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//MARK:
//MARK: Collectioview methods
func collectionView(_ collectionView: UICollectionView,
numberOfItemsInSection section: Int) -> Int {
return arr_img.count
}
func collectionView(_ collectionView: UICollectionView,
cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell",
for: indexPath)
let imgview : UIImageView = cell.viewWithTag(20) as! UIImageView
imgview.image = self.getAssetThumbnail(asset: self.arr_img.object(at: indexPath.row) as! PHAsset, size: 150)
return cell
}
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath)
{
let cell = collectionView.cellForItem(at: indexPath as IndexPath)
if cell!.isSelected == true {
print(indexPath)
cell?.backgroundColor = UIColor.orange
print("Cell is Selected!")
let selectView : UIImageView = cell?.viewWithTag(22) as! UIImageView
selectView.image = UIImage(named: "Select.png")
}
else if cell!.isSelected != true {
collectionView.cellForItem(at: indexPath as IndexPath)
cell?.backgroundColor = UIColor.clear
let selectView : UIImageView = cell?.viewWithTag(22) as! UIImageView
selectView.image = nil
print("Cell is Not Selected!")
}
}
func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
let cell = collectionView.cellForItem(at: indexPath as IndexPath)
print(indexPath)
if cell?.isSelected == true {
cell?.backgroundColor = UIColor.orange
print("Cell is Selected In Deselect!")
let selectView : UIImageView = cell!.viewWithTag(22) as! UIImageView
selectView.image = nil
collectionView.cellForItem(at: indexPath as IndexPath)
}
else if cell?.isSelected != true {
cell?.backgroundColor = UIColor.clear
collectionView.cellForItem(at: indexPath as IndexPath)
print("Cell is DeSelected!")
let selectView : UIImageView = cell!.viewWithTag(22) as! UIImageView
selectView.image = nil
}
}
这些细胞像的tableview细胞再利用。您需要维护一系列已选中的单元格,并在出现单元格后设置打勾图像。 –
为什么写了didDeselectItemAt?因为你的代码只适用于didSelect。 – KKRocks
单元格被重用。将一个属性isSelected添加到模型中,在'didSelect/didDeselect'中更新它,并根据'cellForItem'中的属性设置tick。 – vadian