Ios 在collectionView单元格上添加边框

用户每次单击特定单元格时，该单元格都会有边框。问题是，当我来回滚动时，边框是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
}

以防万一，你正在寻找DIDDENSELECT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
}

---

这是因为细胞的可重用性。您应该在单元格模型中使用属性来跟踪所选状态-

isSelected:Bool

现在在

cellForItem

方法中，如果

isSelected

为

true

，则必须放置if-else并使单元格带边框

这里要注意的是，不要忘记放置else部分并删除else部分中的边框

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
    }

---

由于手机的重复使用，您目前面临着这个问题。要解决这个问题：

---

选择单元格时（在

didSelectItemAt

中），将

indexPath.row

保存在局部变量中。在

cellForRow

方法中，放入如下检查：如果indexath.row==savedValue，则borderColor将为蓝色，否则为正常颜色。

您可以这样使用我的方法：

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 

   }

---

您可以使用“selectedRow”轻松地将边框添加到selectedCell

---

是否仅向选定单元格添加边框？是，仅向选定单元格添加边框。同时也要避免在随机单元格上添加边框。对于那些否决这一点的人，大声说出来。为什么？collectionView.reloadData（）将始终在每次selectedIndexPath更改值时调用？是的，它将在每次单击@jay123456时反映出来

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()
    }
}