take screenshots of each UIViewController

UIViewControllerScreenshot.swift

import UIKit
import AVFoundation

// call this in application(_:didFinishLaunchingWithOptions:)
func setupDebugScreenshot() {
    let from = class_getInstanceMethod(UIViewController.self, #selector(UIViewController.viewDidAppear))
    let to = class_getInstanceMethod(UIViewController.self, #selector(UIViewController.viewDidAppearWithScreenshot))
    method_exchangeImplementations(from, to)
}

extension UIViewController {
    func viewDidAppearWithScreenshot(_ animated: Bool) {
        viewDidAppearWithScreenshot(animated)
        
        guard let view = view, let _ = view.window, let name = NSStringFromClass(type(of: self)).components(separatedBy: ".").last else {
            return
        }
        
        if name.hasPrefix("UI") {
            return
        }
        
        AudioServicesPlaySystemSoundWithCompletion(SystemSoundID(1117), nil) // rec start sound
        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 1.0) {
            takeScreenshot(of: view, filename: name, directory: "ViewControllers")
            AudioServicesPlaySystemSoundWithCompletion(SystemSoundID(1108), nil) // shutter sound
        }
    }
}

private func takeScreenshot(of view: UIView, filename: String, directory: String) {
    // take screen shot
    guard let window = view.window else {
        return
    }
    
    let frame = view.convert(view.bounds, to: window)
    if frame.isEmpty {
        return
    }
    
    UIGraphicsBeginImageContextWithOptions(window.bounds.size, false, UIScreen.main.scale)
    window.drawHierarchy(in: window.bounds, afterScreenUpdates: true)
    
    let context = UIGraphicsGetCurrentContext()
    context?.setStrokeColor(UIColor.red.cgColor)
    context?.setLineWidth(4)
    context?.stroke(frame)
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    
    // create directory if not exist
    guard let documentDirPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first else {
        return
    }
    let dirPath = (documentDirPath as NSString).appendingPathComponent(directory)
    let fm = FileManager.default
    if !fm.fileExists(atPath: dirPath) {
        try? fm.createDirectory(atPath: dirPath, withIntermediateDirectories: true, attributes: nil)
    }
    
    // save
    if let image = image, let data = UIImagePNGRepresentation(image) {
        let savePath = (dirPath as NSString).appendingPathComponent(filename + ".png")
        print(savePath)
        let url = URL(fileURLWithPath: savePath)
        try? data.write(to: url)
    }
}