我该如何转换为这样的通用类型：MyType <ConformingX> （ConformingX是符合协议的类）

Question

how would i achieve this: I want to cast to a generic type with a typeParameter that conforms to a protocol.

I tried the following:

let castedMyType = notCastedMyType as? MyType<X>
let castedMyType = notCastedMyType as? MyType<X> where X: SomeProtocol
let castedMyType = notCastedMyType as? MyType<X where X: SomeProtocol>
let castedMyType = notCastedMyType as? MyType<X: SomeProtocol>

But nothing works.

Here is some example code to get you up and running. Just put it in a Playground:

import Foundation

protocol SomeProtocol{}
class X{}

// example class that conforms to the protocol
class ConformingX: SomeProtocol{}

class BaseType{}
class MyType<X>: BaseType where X: SomeProtocol{}

let notCastedMyType: BaseType = MyType<ConformingX>()

// not working
let castedMyType = notCastedMyType as? MyType<X>
let castedMyType = notCastedMyType as? MyType<X> where X: SomeProtocol
let castedMyType = notCastedMyType as? MyType<X where X: SomeProtocol>
let castedMyType = notCastedMyType as? MyType<X: SomeProtocol>

Answer 1

Ok I found a solution for my complex case. Just add the same generic to the class that is running the code:

class ClassThatRunsTheCode<X> where X: SomeProtocol{

    func executingFunc(){
        // working
        let castedMyType = notCastedMyType as? MyType<X>
    }
}