Weakify / Unownify Methods

Weakify.swift

typealias NoArgMethod<StrongObject, ReturnType> = (StrongObject) -> () -> ReturnType
typealias SingleArgumentMethod<Argument, StrongObject> = (StrongObject) -> (Argument) -> Void

func unown<O, R>(
    _ object: O, // This is strong
    _ method: @escaping NoArgMethod<O, R>
    ) -> () -> R where O: AnyObject, R: Any
{
    return { [unowned object] in
        method(object)()
    }
}

func weakify<O, A>(
    _ object: O, // This is strong
    _ method: @escaping SingleArgumentMethod<A, O>
    ) -> (A) -> Void where O: AnyObject, A: Any
{
    return { [weak object] (argument: A) in
        guard let strongObject = object else { return }
        method(strongObject)(argument)
    }
}