我正在重构 UITableView 在 RxSwift 中的实现。我有不同的 View 项，我想切换它们，以便我能够相应地配置我的数据源。我需要知道哪个单元格类属于哪个 View 项。
为此，我编写了一个方法，它接受一个实现我的 ViewItemProtocol 的项目并返回 AnyClass?。
func getAssociatedtCellType<T>(for item: T) -> AnyClass? where T: ViewItemProtocol {
switch item {
case is TextFieldViewItem: return TextFieldCell.self
case is FaqDetailViewItem: return FaqCell.self
case is HeaderViewItem: return HeaderCell.self
case is SubmitButtonViewItem: return SubmitButtonCell.self
case is BankDetailViewItem: return BankDetailCell.self
case is EmailViewItem: return EmailCell.self
default: return nil
}
}
函数方法配置了我的单元格:
private func configCell<T>(for item: T, with identifier: String, at indexPath: IndexPath) -> UITableViewCell where T: ViewItemProtocol {
guard let cellType = getAssociatedtCellType(for: item.self) else { return UITableViewCell() }
guard let cell = tableView.dequeueReusableCell(withIdentifier: identifier, for: indexPath) as? cellType else { fatalError() }
cell.configureBindings(itemSource: item)
return cell
}
cellType 出现问题:
Use of undeclared type 'cellType'
背后的目标是重构这个方法:
private func dataSource() -> RxTableViewSectionedReloadDataSource<SectionedViewItem> {
let dataSource = RxTableViewSectionedReloadDataSource<SectionedViewItem>(configureCell: { [unowned self] _, tableView, indexPath, item in
switch item {
case let item as TextFieldViewItem:
guard let cell = tableView.dequeueReusableCell(withIdentifier: TextFieldCell.Key, for: indexPath) as? TextFieldCell else { fatalError() }
cell.configureBindings(itemSource: item)
cell.changeButton.isHidden = item.editable
cell.changeButton.addTarget(self, action: #selector(self.showFieldNotEditableAlert), for: .touchUpInside)
cell.textField.addTarget(self, action: #selector(self.textFieldDidChange), for: .editingChanged)
return cell
case let item as FaqDetailViewItem:
guard let cell = tableView.dequeueReusableCell(withIdentifier: FaqDetailCell.Key, for: indexPath) as? FaqDetailCell else { fatalError() }
cell.configureBindings(itemSource: item)
return cell
case let item as PasswordTextFieldViewItem:
guard let cell = tableView.dequeueReusableCell(withIdentifier: PasswordTextFieldCell.Key, for: indexPath) as? PasswordTextFieldCell else { fatalError() }
cell.configureBindings(itemSource: item)
return cell
case let item as HeaderViewItem:
guard let cell = tableView.dequeueReusableCell(withIdentifier: HeaderCell.Key, for: indexPath) as? HeaderCell else { fatalError() }
cell.configureBindings(itemSource: item)
return cell
// ... My other cell types... :-(
})
dataSource.titleForHeaderInSection = { dataSource, index in
let section = dataSource[index]
return section.header
}
return dataSource
}
...变成这样的东西:
private func dataSource() -> RxTableViewSectionedReloadDataSource<SectionedViewItem> {
let dataSource = RxTableViewSectionedReloadDataSource<SectionedViewItem>(configureCell: { [unowned self] _, tableView, indexPath, item in
switch item {
case let item as TextFieldViewItem:
guard let cell = tableView.dequeueReusableCell(withIdentifier: TextFieldCell.Key, for: indexPath) as? TextFieldCell else { fatalError() }
cell.configureBindings(itemSource: item)
cell.changeButton.isHidden = item.editable
cell.changeButton.addTarget(self, action: #selector(self.showFieldNotEditableAlert), for: .touchUpInside)
cell.textField.addTarget(self, action: #selector(self.textFieldDidChange), for: .editingChanged)
return cell
case let item as FaqDetailViewItem, let item as PasswordTextFieldViewItem, let item as HeaderViewItem:
return configCell(for: item, with: "Cell.Key... still to implement)", at: indexPath)
default:
return UITableViewCell()
}
})
dataSource.titleForHeaderInSection = { dataSource, index in
let section = dataSource[index]
return section.header
}
return dataSource
}
最佳答案
不幸的是，这不能在 Swift 中完成。在 swift 中，编译器需要在编译时知道变量的类型，但在您的情况下，您正试图在运行时向下转换。所以不，你不能那样做。
您可能能够在运行时通过泛型进行某种类型的转换来完成它，但是转换不允许您访问该类的属性，这可能是您执行所有绑定(bind)所需要的。我认为您最好将 switch 语句中的代码移动到 tableViewCell 设置中。
关于ios - swift (RxSwift) : Using generics to link ViewItem and Cell classes，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/53498878/