WKWebview Screenshots & Loading/Progress Notification

WKWebViewPlus.swift

//
//  WKWebViewPlus.swift
//
//  Created by Christopher Helf on 19.09.15.
//  Copyright © 2015 Christopher Helf. All rights reserved.
//

import Foundation
import UIKit
import WebKit

@objc protocol WKWebViewPlusDelegate {
    optional func webViewReady()
    optional func webViewProgress(progress: Double)
    optional func webViewScreenshot(view: UIView)
}

class WKWebViewPlus : WKWebView, WKNavigationDelegate {
    
    var statusDelegate : WKWebViewPlusDelegate?
    var originalNavigationDelegate : WKNavigationDelegate?
    var useSnapShot : Bool = false
    
    override init(frame: CGRect, configuration: WKWebViewConfiguration) {
        super.init(frame: frame, configuration: configuration)
        self.initDelegates()
        self.initViewportScript()
    }

    init(frame: CGRect) {
        super.init(frame: frame, configuration: WKWebViewConfiguration())
        self.initDelegates()
        self.initViewportScript()
    }
    
    private func initDelegates() {
        self.addObserver(self, forKeyPath: "estimatedProgress", options: .New, context: nil)
        self.originalNavigationDelegate = self.navigationDelegate
        self.navigationDelegate = self
    }
    
    private func initViewportScript() {
        
        let viewPortjs = "var myCustomViewport = 'width=\(self.frame.size.width)px'; var viewportElement = document.querySelector('meta[name=viewport]');if (viewportElement) {viewportElement.content = myCustomViewport;} else {viewportElement = document.createElement('meta'); viewportElement.name = 'viewport'; viewportElement.content = myCustomViewport;}"
        
        let webViewUserScriptViewPort = WKUserScript(
            source: viewPortjs,
            injectionTime: WKUserScriptInjectionTime.AtDocumentEnd,
            forMainFrameOnly: true
        )
        
        self.configuration.userContentController.addUserScript(webViewUserScriptViewPort)
    }
    
    private func webViewReady() {
        self.scrollView.unloadSwizzle()
        statusDelegate?.webViewReady?()
        makeScreenshot()
    }
    
    func webView(webView: WKWebView, didFinishNavigation navigation: WKNavigation!) {
        self.scrollView.loadSwizzle()
    }
    
    private func webViewProgress(progress: Double) {
        statusDelegate?.webViewProgress?(progress)
    }
    
    private func makeScreenshot() {
        
        guard let _delegate = statusDelegate else {
            return
        }
        
        var view: UIView!
        
        if self.useSnapShot {
            view = self.snapshotViewAfterScreenUpdates(true)
        } else {
            UIGraphicsBeginImageContextWithOptions(self.frame.size, false, 0.0)
            self.drawViewHierarchyInRect(self.frame, afterScreenUpdates: true)
            let snapshot = UIGraphicsGetImageFromCurrentImageContext()
            view = UIImageView(image: snapshot)
            view.frame = self.frame
        }
        
        dispatch_async(dispatch_get_main_queue()) {
            _delegate.webViewScreenshot?(view)
        }
        
    }
    
    override func observeValueForKeyPath(keyPath: String?, ofObject: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
        if keyPath == "estimatedProgress" {
            self.webViewProgress(self.estimatedProgress)
        }
    }
    
    deinit {
        self.removeObserver(self, forKeyPath: "estimatedProgress")
    }
    
}

extension UIScrollView {
    
    func swizzleMethod(originalSelector: Selector, swizzledMethod: Selector){
        let original = class_getInstanceMethod(object_getClass(self), originalSelector)
        let swizzled = class_getInstanceMethod(object_getClass(self), swizzledMethod)
        method_exchangeImplementations(original, swizzled);
    }
    
    func loadSwizzle() {
        self.swizzleMethod(Selector("setContentSize:"), swizzledMethod: ("setContentSizeSwizzled:"))
    }
    
    func unloadSwizzle() {
        self.swizzleMethod(Selector("setContentSizeSwizzled:"), swizzledMethod: ("setContentSize:"))
    }
    
    func setContentSizeSwizzled(contentSize : CGSize) {
        
        self.setContentSizeSwizzled(contentSize)
        
        if let webview = self.superview as? WKWebViewPlus {
            if contentSize.height != 0 && contentSize.width != 0 {
                webview.webViewReady()
            }
        }
    }
    
}

If it has a demo , it will be more helpful .