Duplicate codes in Controller - ios

Question

I am currently working on one project. It may potentially have duplicated codes in multiple controllers like below.
Controller A
class A: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
// about 50~70 lines of codes
#IBAction func scanButtonTapped {
// used self (as AVCaptureMetadataOutputObjectsDelegate)
// used view
// called presentViewController(...), which is a func in UIViewController
}
}
Controller B
class B: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
#IBAction func scanButtonTapped {
// will need same logic as in Controller A
}
}
My current solution is have another class C, and move the duplicated codes into it. However, if I do so, controller can cast to AVCaptureMetadataOutputObjectsDelegate, but not to UIViewController.
class C {
func btnTapped (view: UIView, controller: AnyClass) {
// logic is here
// controller can cast to AVCaptureMetadataOutputObjectsDelegate
// but controller cannot cast to UIViewController
}
}
so A and B will have
class A {
#IBAction func scanButtonTapped {
let c = C()
c.btnTapped(view, self)
}
}
My question is if it is possible to cast controller into UIViewController. OR is there another way to refactor the codes properly?

Answer 1

What about extend AVCaptureMetadataOutputObjectsDelegate protocol and create default implementation by protocol extension (POP approach)?
protocol ScanButtonClickable: AVCaptureMetadataOutputObjectsDelegate {
func btnTapped() // this line is optional
}
extension Clickable where Self: UIViewController {
func btnTapped() {
// logic is here
}
}
class A: UIViewController, ButtonClickable {
...
}
class B: UIViewController, ButtonClickable {
...
}

Answer 2

Try this:
//declare your default method to be used across classes
protocol MyProtocol {
func myFunc()
}
//provide the implementation of your default behavior here in myFunc()
extension MyProtocol {
func myFunc() {
print("Default behavior")
}
}
class A: MyProtocol {
}
class B: MyProtocol {
}
let a = A()
a.myFunc()
let b = B()
b.myFunc()
//prints
Default behavior
Default behavior