In short, add <T> after the function name, pass in a parameter with type T.Type, and when you need to use that parameter, usually you call the name of the parameter, but instead, you use the type T

Pass in Type as Parameter

Why do I need to pass in types as a parameter? One of the usage case is I want to dynamically cast some objects depending to what I passed in.

How?

Here is a useful reference I found.

In short, add <T> after the function name, pass in a parameter with type T.Type, and when you need to use that parameter, usually you call the name of the parameter, but instead, you use the type T

Call class method when pass in custom object

Here is a useful reference I found.

In short, create a protocol with the method you want to call and adapt to the protocol in that custom object, then when you create a function that pass in the type T, assign the protocol to that type, then its good to go.

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protocol MethodProtocol {
  func someMethod() -> ()
}

class customObject {
  // your class
}

extension customObject: MethodProtocol {
  func someMethod() -> () {
    print("Method I want to call")
  }
}

func passInType<T: MethodProtocol>(type: T.Type) {
  T.someMethod()
}