无法使用其他符合协议的协议来遵守协议

Question

我遇到了以下代码，不确定为什么不编译：

protocol CellDelegate: class {}

protocol DelegatingCellViewModel {
    var delegate: CellDelegate? { get }
}

protocol ProductCellViewModelDelegate: CellDelegate {}

// Error: Type 'ProductCellViewModel' does not conform to protocol 'DelegatingCellViewModel'
class ProductCellViewModel: DelegatingCellViewModel {
    weak var delegate: ProductCellViewModelDelegate?
}

完整错误消息：

error: Playground.playground:9:7: error: type 'ProductCellViewModel' does not conform to protocol 'DelegatingCellViewModel'
class ProductCellViewModel: DelegatingCellViewModel {
      ^

Playground.playground:10:14: note: candidate has non-matching type 'ProductCellViewModelDelegate?'
    weak var delegate: ProductCellViewModelDelegate?
             ^

Playground.playground:4:9: note: protocol requires property 'delegate' with type 'CellDelegate?'; do you want to add a stub?
    var delegate: CellDelegate? { get }
        ^

这是语言限制吗？还是我缺少什么？ 应该如何编写此代码，以便对其进行编译并保持其意图？

Answer 1

您需要更改委托的类型或添加协议存根。

class ProductCellViewModel: DelegatingCellViewModel {
    weak var delegate: CellDelegate?
}

或 您必须像这样更改该特定委托的名称。因为委托名称已经被符合协议使用-

class ProductCellViewModel: DelegatingCellViewModel {
    var delegate: CellDelegate?
    weak var productDelegate: ProductCellViewModelDelegate?
}