Question

每次用户点击特定单元格时，单元格都会有边框。问题是当我来回滚动时，边框选择随机单元格来设置边框。

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    let cell = collectionView.cellForItem(at: indexPath)
    cell?.layer.borderColor = UIColor.blue.cgColor
    cell?.layer.borderWidth = 1
}

以防您正在寻找didDeselect部分

func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
    let cell = collectionView.cellForItem(at: indexPath)
    cell?.layer.borderColor = UIColor.clear.cgColor
    cell?.layer.borderWidth = 1
}

Answer 1

这是因为细胞的可重用性。您应该在单元格模型中获取属性以跟踪选定的状态 - isSelected: Bool

现在在cellForItem方法中，如果isSelected为true，则必须放置if else并使您的单元格边界化。

请注意，请勿忘记在其他部分放置其他部分并删除边框。

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    let cell = collectionView.cellForItem(at: indexPath)
    cell?.layer.borderColor = UIColor.blue.cgColor
    cell?.layer.borderWidth = 1
    cell?.isSelected = true
}


func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
    let cell = collectionView.cellForItem(at: indexPath)
    cell?.layer.borderColor = UIColor.clear.cgColor
    cell?.layer.borderWidth = 1
    cell?.isSelected = false
}


override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)
        ...
        ...
        if cell.isSelected {
            //put border logic
        }else {
            // remove border
        }
        return cell
    }

Answer 2

您可以使用＆＃34; selectedRow＆＃34;。

轻松地将边框添加到selectedCell

import UIKit

class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {

    var selectedRow = -1

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 10
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)

        if selectedRow == indexPath.row {
            cell.layer.borderColor = UIColor.blue.cgColor
            cell.layer.borderWidth = 1
        }
        else {
            cell.layer.borderWidth = 0
        }

        return cell
    }

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        if selectedRow == indexPath.row {
           selectedRow = -1
        } else {
            selectedRow = indexPath.row
        }
        collectionView.reloadData()
    }
}

Answer 3

你可以这样用我的方式：

var selectedIndexPath: NSIndexPath{
    didSet{
        collectionView.reloadData()
    }
}

func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
selectedIndexPath = indexPath
}

     func collectionView(_ collectionView: UICollectionView,
                    cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

        var borderColor: CGColor! = UIColor.clear.cgColor
        var borderWidth: CGFloat = 0

        if indexPath == selectedIndexPath{
            borderColor = UIColor.brown.cgColor
            borderWidth = 1 //or whatever you please
        }else{
            borderColor = UIColor.clear.cgColor
            borderWidth = 0
        }

        cell.layer.borderWidth = borderWidth //You can use your component
        cell.layer.borderColor = borderColor 

   }

Answer 4

由于细胞重复使用，您目前正面临此问题。要解决这个问题：

选择单元格（在didSelectItemAt中）时，将indexPath.row保存在局部变量中。在cellForRow方法中，检查如下：if indexPath.row == savedValue，borderColor将为蓝色，否则为正常颜色。

在collectionView单元格上添加边框

4 个答案: