Create instance from class using other class

So i came across this case, an already published application needed to change all of it's API's & Models.

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Now i have created a generic tier to handle the requests and apis and almost mid way into implementing all the services, now i came across this problem, the previous defined models are used widely around the application of course and since its MVC , Massive View Controller. it is going to cost me too much changing everything in each scene to the new model type,
therefore i thought of making an adapter to cast the new models when i get them in my callback closure to the old ones type.

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I have already figured out a way but the problem its pretty much long, long way i am looking for a better approach if existed and a better solution over all for the case if there was a better one.

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protocol Parsable {
    var time: String { get }
    var span: String { get }
    init(_ copy: Parsable)
}

class Foo: Parsable {
    required init(_ copy: Parsable) {
        self.span =  copy.span
        self.time =  copy.time
    }

    init(time: String, span: String) {
        self.time = time
        self.span = span
    }
    var time = ""
    var span = ""
}

class Fee: Parsable {
    required init(_ copy: Parsable) {
        self.span =  copy.span
        self.time = copy.time
    }
    init(time: String, span: String, date: String) {
        self.time = time
        self.span = span
        self.date = date // an extra var that is not used in Foo
    }
    var time = ""
    var span = ""
    var date = ""
}

var foo = Foo(time: "", span: "")
var fee = Fee(time: "2", span: "ye", date: "123")
// Usage
var deeped = Foo(fee)

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As you can tell from the code i've created a protocol that contains the variables and an init() that holds its type, now imagine this to implement a model with +50 variable and +40 model in total, might need an age or two.