How does one effectively utilize Apple's xcode swift documentation?

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Xcode

Swift

I am a Swift and Xcode beginner, and I have read Apple's "The Swift Programming Language" and understand the fundamentals of Swift quite well. But when I try to refer to the documentation to know what functions to call, etc to do something not often done (such as using Replay Kit) I run into trouble trying to use it. I've tried using code exactly as specified in Apple's "Documentation and API Reference" but the code doesn't execute properly or even at all. For example, using the exact functions specified here: [https://developer.apple.com/reference/replaykit/rpscreenrecorder] doesn't do anything at all.

import UIKit
import ReplayKit

class ViewController: UIViewController, RPPreviewViewControllerDelegate {
    

    @IBAction func startRecording(_ sender: Any) {
        
        func startRecording(handler: ((Error?) -> Void)? = nil){
           
        }

    }
    

    @IBAction func stopRecording(_ sender: Any) {
        
        func stopRecording(handler: ((RPPreviewViewController?, Error?) -> Void)? = nil){
            
        }
    }
    
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
     
    }


}

What I have tried:

Pasting relevant code in Xcode from the documentation