在 NSCoder 中展开可选值时意外发现 nil

Posted 2023-03-14

【中文标题】在 NSCoder 中展开可选值时意外发现 nil

【英文标题】：Unexpectedly found nil while unwrapping an Optional value in NSCoder

【发布时间】：2017-09-25 08:11:02

【问题描述】：

isSelected(Bool) 出现零错误。请查看下面的屏幕截图以获取更多详细信息。

导入基础

class StatusEntity: `NSObject`, `NSCoding` 

    var Value: String
    var Native_Description: String
    var isSelected: Bool

    override init() 
        Value = ""
        Native_Description = ""
        isSelected = false
    

    @objc required init(coder aDecoder: NSCoder) 
        Value = aDecoder.decodeObject(forKey: "Value") as! String
        Native_Description = aDecoder.decodeObject(forKey: "Native_Description") as! String
        isSelected = aDecoder.decodeObject(forKey: "isSelected") as! Bool
    

    @objc func encode(with aCoder: NSCoder) 
        aCoder.encode(Value, forKey: "Value")
        aCoder.encode(Native_Description, forKey: "Native_Description")
        aCoder.encode(isSelected, forKey: "isSelected")
    

这是CollectionView 代码

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

        let cell: StatusCheckCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "statusCollectionCell", for: indexPath) as! StatusCheckCollectionViewCell

        let entity: StatusEntity = arrayList[indexPath.item]
        cell.txtName.text = entity.Native_Description

        // Making CollectionView Cell Right Align
        var scalingTransform : CGAffineTransform!
        scalingTransform = CGAffineTransform(scaleX: -1, y: 1);
        cell.transform = scalingTransform
        cell.btnItem.tag = indexPath.row
        cell.btnItem.addTarget(self, action: #selector(StatusTableViewCell.onItemClicker(_:)), for: UIControlEvents.touchUpInside)

        if(entity.isSelected)
            cell.imgCheckBox.image = UIImage(named: "CheckBoxSelected")
         else 
            cell.imgCheckBox.image = UIImage(named: "CheckBox")
        
        return cell
    

    func onItemClicker(_ sender: UIButton)
        let entity: StatusEntity = arrayList[sender.tag]
        entity.isSelected = !entity.isSelected
        let indexPath: IndexPath = IndexPath(row: sender.tag, section: 0)
        collectionView.reloadItems(at: [indexPath])

        // Saving values to DB
        var submitEntity: SubmitDocumentEntity = SubmitDocumentEntity()
        let insertEntity = dataStorage.getSubmitDocumentEntity()
        if(!insertEntity.isKind(of: NSNull.self))
            submitEntity = dataStorage.getSubmitDocumentEntity() as! SubmitDocumentEntity
        
        if(entity.isSelected) 
            if(!submitEntity.TransactionTypes.contains(entity.Value))
                submitEntity.TransactionTypes.append(entity.Value)
            
         else 
            if(submitEntity.TransactionTypes.contains(entity.Value))
                let index = submitEntity.TransactionTypes.index(of: entity.Value)
                submitEntity.TransactionTypes.remove(at: index!)
            
        
        dataStorage.putSubmitDocumentEntity(submitEntity)
    

【问题讨论】：

@vadian 感谢更新和回答。

【参考方案1】：

您将解码一个对象。就NSCoding 而言，Bool 不是 对象。

原始类型有专门的方法。

isSelected = aDecoder.decodeBool(forKey: "isSelected")

请遵守变量名以小写字母开头并且是camelCased而不是snake_cased

的命名约定