Duplicate codes in Controller

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 {
...
}