This is a handy class that you can use to save an image to your photos library and below there is an example of how to use it. IMPORTANT: You must provide a message in "Privacy - Photo Library Additions Usage Description" of your target info in order to be able to use this class!

ImageSaver.swift

import UIKit

class ImageSaver: NSObject {
    var successHandler: (() -> Void)?
    var errorHandler: ((Error) -> Void)?
    
    func writeToPhotoAlbum(image: UIImage) {
        UIImageWriteToSavedPhotosAlbum(image, self, #selector(saveCompleted), nil)
    }
    
    @objc func saveCompleted(_ image: UIImage, didFinishSavingWithError error: Error?, contextInfo: UnsafeRawPointer) {
        if let error = error {
            errorHandler?(error)
        } else {
            successHandler?()
        }
    }
}

SaveImageExample.swift

// How to use it
import SwiftUI

struct SaveImageExample: View {
    @State private var image: UIImage?
    
    var body: some View {
        VStack {
            Image(uiImage: image ?? UIImage())
                .resizable()
                .scaledToFit()
                .onAppear(perform: loadImage)
            
            Button("Save Image", action: save)
        }
    }
    func loadImage() {
        image = UIImage(named: "Example")
    }
    func save() {
        guard let image = image else { return }
        
        let imageSaver = ImageSaver()
        
        imageSaver.successHandler = {
            // Show a success alert to user
        }
        imageSaver.errorHandler = { error in
            // Show a error alert to user
        }
        imageSaver.writeToPhotoAlbum(image: image)
    }
}