UICollectionView和Selected Cell在滚动时丢失选择

Question

我有一个UICollectionView,一切都工作正常,但是,有一件事我无法处理(我不知道如何),我有一个单元格的集合,以查看用户需要向下或向上滚动的所有单元格像往常一样.

当用户选择单元格时,内容变为"红色",红色是"选定"单元格,黑色是"未选定"单元格或正常状态.

当所选单元格落在navigationBar或TabBar后面时,单元格会丢失"红色"并再次变为黑色,如"未选中".

当uicollectionview滚动时,当细胞落后时,我怎么能保持"红色"？

override func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
    let cell = collectionView.cellForItemAtIndexPath(indexPath)

    let icon = cell!.viewWithTag(10) as? UIImageView
    icon!.image = icon!.image! .imageWithRenderingMode(UIImageRenderingMode.AlwaysTemplate)
    icon!.tintColor = UIColor.redColor()

    let label = cell!.viewWithTag(100) as? UILabel
    label?.textColor = UIColor.redColor()
    //print("Seleccionado")

}

override func collectionView(collectionView: UICollectionView, didDeselectItemAtIndexPath indexPath: NSIndexPath) {
    let cell = collectionView.cellForItemAtIndexPath(indexPath)

    cell!.contentView.backgroundColor = nil
    cell!.contentView.layer.borderColor = nil

    let icon = cell!.viewWithTag(10) as? UIImageView
    icon!.image = icon!.image! .imageWithRenderingMode(UIImageRenderingMode.AlwaysTemplate)
    icon!.tintColor = UIColor.blackColor()

    let label = cell!.viewWithTag(100) as? UILabel
    label?.textColor = UIColor.lightGrayColor()
    //print("Unselect")
}

override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! ObjectosCollectionViewCell

    cell.objectoNameLabel.text = objectosData[indexPath.row]
    cell.objectoNameLabel.textColor = UIColor.lightGrayColor()
    cell.objectoImageView.image = UIImage(named:objectosImage[indexPath.row])

    return cell
}

谢谢

Answer 1

您需要对逻辑进行一些修改;

//CollectionViewCell Custom Class
import UIKit

class CollectionViewCell: UICollectionViewCell {

    override var selected: Bool {
        get {
            return super.selected;
        }

        set {
            if (super.selected != newValue) {
                super.selected = newValue

                let icon = self.viewWithTag(10) as? UIImageView
                icon?.image = icon?.image!.imageWithRenderingMode(UIImageRenderingMode.AlwaysTemplate)

                let label = self.viewWithTag(100) as? UILabel

                if (newValue == true) {
                    icon?.tintColor = UIColor.redColor()
                    label?.textColor = UIColor.redColor()
                } else {
                    icon?.tintColor = UIColor.blackColor()
                    label?.textColor = UIColor.lightGrayColor()
                }
            }
        }
    } //P.E.

}

然后;

//Define a class variable in your viewController
var cellStatus:NSMutableDictionary = NSMutableDictionary();

//Collection view delegate methods
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

    var cell:CollectionViewCell? = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as? CollectionViewCell;

    cell!.selected = (cellStatus[indexPath.row] as? Bool) ?? false;

    return cell!;
}

func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
    //Updating cell status
    let cell = collectionView.cellForItemAtIndexPath(indexPath)
    cell?.selected = true;

    //Updating dic
    self.cellStatus[indexPath.row] = true;
}

func collectionView(collectionView: UICollectionView, didDeselectItemAtIndexPath indexPath: NSIndexPath) {
    //Updating cell status
    let cell = collectionView.cellForItemAtIndexPath(indexPath)
    cell?.selected = false;

    //Updating dic
    self.cellStatus[indexPath.row] = false;
}

注意:更改图像图标颜色的方法并不好.它需要太多的处理能力,可能会挂起滚动.每个州应该使用两个单独的图像.