Create Snapshot for ScrollView (Views) SwiftUI

HostSnapshoptViewController.swift

//
//  HostSnapshoptViewController.swift
//  git:pabloruan0710
//
//  Created by Pablo Ruan on 28/04/23.
//  Copyright © 2023 Pablo Ruan. All rights reserved.
//

import Foundation
import SwiftUI
import UIKit

/**
 
 For use in SwiftUI:
 
     ScrollView {
 
     }.onTapGesture {
         let image = self.snapshot()
         shareItem = [image]
     }
 
 */

class HostSnapshoptViewController<Content>: UIHostingController<Content> where Content: View {
    
    private lazy var scrollView: UIScrollView = {
        let scrollView = UIScrollView()
        scrollView.translatesAutoresizingMaskIntoConstraints = false
        return scrollView
    }()
    
    private lazy var stackView: UIStackView = {
        let stack = UIStackView()
        stack.axis = .vertical
        stack.distribution = .fillProportionally
        stack.translatesAutoresizingMaskIntoConstraints = false
        return stack
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        buildViewHierarchy()
        addConstraints()
        addChildView()
    }
    
    private func buildViewHierarchy() {
        view.addSubview(scrollView)
        scrollView.addSubview(stackView)
    }
    
    private func addConstraints() {
        NSLayoutConstraint.activate([
            scrollView.topAnchor.constraint(equalTo: view.topAnchor),
            scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
            
            stackView.topAnchor.constraint(equalTo: scrollView.topAnchor),
            stackView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor),
            stackView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor),
            stackView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor),
            stackView.widthAnchor.constraint(equalTo: view.widthAnchor)
        ])
    }
    
    private func addChildView() {
        let child = UIHostingController(rootView: rootView)
        addChildViewController(child)
        if let view = child.view {
            view.translatesAutoresizingMaskIntoConstraints = false
            stackView.addArrangedSubview(view)
        }
        child.didMove(toParent: self)
        scrollView.layoutIfNeeded()
    }
    
    // MARK: Public APIs
    public func getSize() -> CGSize {
        scrollView.layoutIfNeeded()
        return scrollView.contentSize
    }
    
    public func snapshot() -> UIImage {
        let savedContentOffset = scrollView.contentOffset
        scrollView.contentOffset = CGPoint.zero
        let image = scrollView.asImage()
        scrollView.contentOffset = savedContentOffset
        return image
    }
}

extension View {
    func snapshot() -> UIImage {
        let controller = HostSnapshoptViewController(rootView: self)
        let targetSize = controller.getSize()
        let bounds = CGRect(origin: .zero, size: targetSize)
        let window = UIWindow(frame: bounds)
        window.rootViewController = controller
        window.makeKeyAndVisible()
        let image = controller.snapshot()
        return image
    }
}

extension UIView {
  func asImage() -> UIImage {
    let renderer = UIGraphicsImageRenderer(bounds: bounds)
    return renderer.image { rendererContext in
      layer.render(in: rendererContext.cgContext)
    }
  }
}

It seems that's the max height of image is limited to the screen height because only 38 indexes are visible with the code below:

let image = ScrollView{
    ForEach(1..<100) { index in
            Text("index: \(index)")
    }
}.snapshot()

iOS 17 Public beta and Xcode-15-beta 7