swift - Swift 中的批量初始化和协议(protocol)

Question

我有那些协议(protocol)

protocol BaseProtocol: CustomStringConvertible {
   var aVar: Int? {get set}
}

protocol ProtocolA: BaseProtocol {
    init(number: Int)
}

protocol ProtocolB: BaseProtocol {
    init(number: Int, string: String)
}

我有课:

• ClassAOne, ClassATwo, ClassAThree 符合ProtocolA
• ClassBOne, ClassBTwo, ClassBThree 符合ProtocolB

所以我想要的是写一个批量初始化。这是我想要的示例:

let arrayOfClasses: [Any] = [ClassAOne.self, ClassATwo.self, ClassBThree.self, ClassAThree]

let number = 10
let text = "test"

let initializedObjects = arrayOfClasses.map { classType in
    // This code isn't compilable
    // If class type is a class which conform to ProtocolA - use simple init
    if let protocolA = classType as? ProtocolA {
        return ProtocolA.init(number: number)
    } 
    // If class type is a class which conform to ProtocolB - use longer init
    if let protocolB = classType as? ProtocolB {
        return ProtocolB.init(number: number, string: text)
    }
}

有可能吗？基本上我有 Class.self 数组作为输入，我想有初始化对象数组作为输出。

Answer 1

是的，但在我看来，结果非常丑陋。 initializedObjects 必须是 [Any]，这是一个可怕的类型(而且 Any? 可能会悄悄出现，这更糟糕).我真的建议只按类型拆分类，除非这会引起严重的头痛。也就是说，探索类型如何在 Swift 中工作是可能的，也是一种有益的探索。

let initializedObjects = arrayOfClasses.flatMap { classType -> Any? in
    switch classType {
    case let protocolA as ProtocolA.Type:
        return protocolA.init(number: number)

    case let protocolB as ProtocolB.Type:
        return protocolB.init(number: number, string: text)

    default:
        return nil // Or you could make this return `Any` and fatalError here.
    }
}