Webpage isn't displayed using WkWebView and Swift in iOS - ios

Question

I am using iOS9 and XCode7.2 to make my app display a webpage using WkWebView and Swift.
To eliminate possible errors, I have created an XCode project that has only the following code and there is nothing in Main.storyboard.
The weird thing is that the webpage only shows up "1 time" after I ran the code over and over the past few days. Two members on StackOverflow confirmed that the code works for XCode 8 / Swift 3, and Xcode 7.3.1 / iOS 9.3 simulator.
Is my xCode too old or what other problems might cause it?
import UIKit
import WebKit
class WebViewController: UIViewController {
#IBOutlet var containerView : UIView!
var webView: WKWebView?
override func loadView() {
super.loadView()
self.webView = WKWebView()
self.view = self.webView!
}
override func viewDidLoad() {
super.viewDidLoad()
let url = NSURL(string: "https://www.yahoo.com")!
let req = NSURLRequest(URL: url)
self.webView!.loadRequest(req)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
}

Answer 1

Step : 1 Import webkit in ViewController.swift
import WebKit
Step : 2 Declare variable of webView.
var webView : WKWebView!
Step : 3 Adding Delegate of WKNavigationDelegate
class ViewController: UIViewController , WKNavigationDelegate{
Step : 4 Adding code in ViewDidLoad.
let myBlog = "https://www.google.com/"
let url = NSURL(string: myBlog)
let request = NSURLRequest(URL: url!)
// init and load request in webview.
webView = WKWebView(frame: self.view.frame)
webView.navigationDelegate = self
webView.loadRequest(request)
self.view.addSubview(webView)
self.view.sendSubviewToBack(webView)

Answer 2

The correct way with auto layout for all device:
import UIKit
import WebKit
class ViewController: UIViewController, WKUIDelegate {
let webView = WKWebView()
override func viewDidLoad() {
super.viewDidLoad()
setupWebView()
}
fileprivate func setupWebView() {
webView.uiDelegate = self
webView.translatesAutoresizingMaskIntoConstraints = false
DispatchQueue.main.async {
guard let url = URL(string: "http://www.apple.com") else { return }
self.webView.load(URLRequest(url: url))
}
view.addSubview(webView)
webView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
webView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor).isActive = true
webView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor).isActive = true
webView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true
}}
in info.plist:
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<true/>
</dict>