Capture UITableView full content.

UIViewController.swift

//
//  ViewController.swift
//  UIViewCapture
//
//  Created by Yusuke on 11/7/16.
//  Copyright © 2016 Yusuke. All rights reserved.
//

import UIKit

extension UIView {
    
    func captureImage() -> UIImage? {
        
        UIGraphicsBeginImageContextWithOptions(bounds.size, false, 0.0)

        guard let context: CGContext = UIGraphicsGetCurrentContext() else { return nil }
        
        self.layer.render(in: context)
        
        let capturedImage: UIImage? = UIGraphicsGetImageFromCurrentImageContext()
        
        UIGraphicsEndImageContext()
        
        return capturedImage
    }
}

extension UITableView {

    var contentBottom: CGFloat {
        return contentSize.height - bounds.height
    }
    
    override func captureImage() -> UIImage? {

        let images = captureImages()
        
        // Concatenate images
        
        UIGraphicsBeginImageContext(contentSize);
        
        var y: CGFloat = 0
        for image in images {
            image.draw(at: CGPoint(x: 0, y: y))
            y = min(y + bounds.height, contentBottom) // calculate layer diff
        }
        let concatImage = UIGraphicsGetImageFromCurrentImageContext();
        
        UIGraphicsEndImageContext();
        
        return concatImage
    }
    
    func captureImages() -> [UIImage] {
        
        var images: [UIImage?] = []
        
        while true {
            
            images.append(superview?.captureImage()) // not work in self.view
            
            if contentOffset.y < (contentBottom - bounds.height) {
                contentOffset.y += bounds.height
            } else {
                contentOffset.y = contentBottom
                images.append(superview?.captureImage()) // not work in self.view
                break
            }
        }
        
        return images.flatMap{ $0 } // exclude nil
    }
}

class ViewController: UIViewController, UITableViewDataSource {
    
    @IBOutlet weak var tableView: UITableView!

    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        if let image = self.tableView.captureImage() {
            UIImageWriteToSavedPhotosAlbum(image, self, #selector(didFinishWriteImage(_:error:contextInfo:)), nil)
        }
    }
    
    // MARK: - UIImageWriteToSavedPhotosAlbum
    
    func didFinishWriteImage(_ image: UIImage, error: NSError?, contextInfo: UnsafeMutableRawPointer) {
        if let error = error {
            print("Image write error: \(error)")
        }
    }

    // MARK: - UITableViewDataSource
    
    public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 60
    }
    
    public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        
        guard let cell = tableView.dequeueReusableCell(withIdentifier: "Cell") else { return UITableViewCell() }
        cell.textLabel?.text = "Index: \(indexPath.row)"
        return cell
    }
}