Implement main webView functionality

- functionality for adding and deleting web views
- functionality for typing addresses in the search bar and triggering page loads in the active web view

31-ipad-multitasking/Multibrowser/Multibrowser/Base.lproj/Main.storyboard

@@ -40,15 +40,29 @@
                         </constraints>
                         <viewLayoutGuide key="safeArea" id="6Tk-OE-BBY"/>
                     </view>
-                    <navigationItem key="navigationItem" id="nfO-E2-nuf"/>
+                    <navigationItem key="navigationItem" id="nfO-E2-nuf">
+                        <rightBarButtonItems>
+                            <barButtonItem systemItem="add" id="D7y-wQ-NkI">
+                                <connections>
+                                    <action selector="addWebView:" destination="BYZ-38-t0r" id="qBD-ti-G5m"/>
+                                </connections>
+                            </barButtonItem>
+                            <barButtonItem systemItem="trash" id="nBz-Mn-Hrb">
+                                <connections>
+                                    <action selector="deleteWebView:" destination="BYZ-38-t0r" id="zJa-Jg-Fk1"/>
+                                </connections>
+                            </barButtonItem>
+                        </rightBarButtonItems>
+                    </navigationItem>
                     <connections>
                         <outlet property="addressBar" destination="jYU-dR-unr" id="9D7-0X-x74"/>
+                        <outlet property="deleteWebViewButton" destination="nBz-Mn-Hrb" id="JrK-bc-UYZ"/>
                         <outlet property="stackView" destination="Wqs-Qr-mVC" id="6eG-0Q-lNL"/>
                     </connections>
                 </viewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/>
             </objects>
-            <point key="canvasLocation" x="934.53237410071949" y="133.81294964028777"/>
+            <point key="canvasLocation" x="939" y="134"/>
         </scene>
         <!--Navigation Controller-->
         <scene sceneID="sYu-kN-pLc">

31-ipad-multitasking/Multibrowser/Multibrowser/HomeViewController.swift

@@ -7,16 +7,128 @@
 //
 
 import UIKit
+import WebKit
+
+let defaultTitle = "Web View Wonderland"
 
 class HomeViewController: UIViewController {
     @IBOutlet weak var addressBar: UITextField!
     @IBOutlet weak var stackView: UIStackView!
+    @IBOutlet weak var deleteWebViewButton: UIBarButtonItem!
+    
+    lazy var defaultURL = URL(string: "https://developer.apple.com/develop/")!
+    
+    weak var activeWebView: WKWebView! {
+        didSet {
+            activeWebViewChanged()
+        }
+    }
     
     override func viewDidLoad() {
         super.viewDidLoad()
         // Do any additional setup after loading the view, typically from a nib.
+        addressBar.delegate = self
+        setupDefaultUI()
     }
+    
+    
+    func activeWebViewChanged() {
+        if activeWebView == nil {
+            setupDefaultUI()
+        } else {
+            title = activeWebView.title
+            deleteWebViewButton.isEnabled = true
+            
+            for view in stackView.arrangedSubviews {
+                view.layer.borderWidth = 0
+            }
+            
+            activeWebView.layer.borderWidth = 3
+        }
+    }
+    
+    
+    func setupDefaultUI() {
+        deleteWebViewButton.isEnabled = false
+        title = defaultTitle
+    }
+    
+    func replaceActiveWebView(afterDeletingFromIndex previousIndex: Int) {
+        if stackView.arrangedSubviews.isEmpty {
+            activeWebView = nil
+        } else {
+            // if that was the last web view in the stack, move the index back one
+            let targetIndex = min(previousIndex, stackView.arrangedSubviews.count - 1)
 
+            activeWebView = stackView.arrangedSubviews[targetIndex] as? WKWebView ?? nil
+        }
+    }
+    
+    
+    @IBAction func deleteWebView(_ sender: Any) {
+        guard activeWebView != nil else { return }
+        
+        if let index = stackView.arrangedSubviews.firstIndex(of: activeWebView) {
+            stackView.removeArrangedSubview(activeWebView)
+            activeWebView.removeFromSuperview()
+            
+            replaceActiveWebView(afterDeletingFromIndex: index)
+        }
+    }
+    
+    
+    @IBAction func addWebView(_ sender: Any) {
+        let webView = WKWebView()
+        let gestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(webViewTapped))
+        
+        webView.navigationDelegate = self
+        webView.layer.borderColor = UIColor.blue.cgColor
+        
+        gestureRecognizer.delegate = self
+        webView.addGestureRecognizer(gestureRecognizer)
+        
+        stackView.addArrangedSubview(webView)
+        webView.load(URLRequest(url: defaultURL))
 
+        activeWebView = webView
+    }
 }
 
+
+extension HomeViewController: WKNavigationDelegate {
+    
+}
+
+
+
+extension HomeViewController: UITextFieldDelegate {
+    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
+        if activeWebView != nil, let address = addressBar.text {
+            if let url = URL(string: address) {
+                activeWebView.load(URLRequest(url: url))
+            }
+        }
+        
+        textField.resignFirstResponder()
+        return true
+    }
+}
+
+
+extension HomeViewController: UIGestureRecognizerDelegate {
+    /**
+     Tell iOS we want our own gesture recognizer to trigger alongside the recognizers built in to each WKWebView
+     */
+    func gestureRecognizer(
+        _ gestureRecognizer: UIGestureRecognizer,
+        shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer
+    ) -> Bool {
+        return true
+    }
+    
+    @objc func webViewTapped(sender: UITapGestureRecognizer) {
+        if let webView = sender.view as? WKWebView {
+            activeWebView = webView
+        }
+    }
+}