How to Detect Back Swipe in WkWebView - ios

Question

Is it possible to detect a back swipe in a web view when there has not been any forward navigation? The following code works fine if the user has moved off the first page but I want to know if they back swiped while on that page.
Update - This is the code I'm using after modifying it per comments. I added the navigation back function and the swipe gesture.
class WebViewClient: UIViewController, WKUIDelegate, WKNavigationDelegate, UIGestureRecognizerDelegate
{
var webView: WKWebView!
public func load(pageLink page: String)
{
print("Opening: " + page)
if webView != nil
{
if let myURL = URL(string:page)
{
webUrlRequest = page
let myRequest = URLRequest(url: myURL)
webView.load(myRequest)
}
}
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!)
{
print("Opened: " + webUrlRequest)
}
override func loadView()
{
let pref = WKPreferences()
pref.javaScriptEnabled = true
let config = WKWebViewConfiguration()
config.preferences = pref
webView = WKWebView(frame: .zero, configuration: config)
webView.uiDelegate = self
webView.navigationDelegate = self
webView.allowsBackForwardNavigationGestures = true
view = webView
}
func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: #escaping (WKNavigationActionPolicy) -> Void)
{
if navigationAction.navigationType == .backForward && webView.backForwardList.backList.count == 0
{
print("Can't go back any more")
}
decisionHandler(.allow)
}
#objc func backNavigationFunction(_ sender: UIScreenEdgePanGestureRecognizer)
{
let dX = sender.translation(in: view).x
if sender.state == .ended
{
let fraction = abs(dX / view.bounds.width)
if fraction >= 0.35
{
print("Back swipe")
//back navigation code here
}
}
}
override func viewDidLoad()
{
super.viewDidLoad()
let swipeGesture = UIScreenEdgePanGestureRecognizer(target: self, action: #selector(backNavigationFunction(_:)))
swipeGesture.edges = .left
swipeGesture.delegate = self
webView.addGestureRecognizer(swipeGesture)
}
}

Answer 1

I would implement a UIScreenEdgePanGestureRecognizer to handle this. Add the following to your viewDidLoad
let swipeGesture = UIScreenEdgePanGestureRecognizer(target: self, action: #selector(backNavigationFunction(_:)))
swipeGesture.edges = .left
swipeGesture.delegate = self
view.addGestureRecognizer(swipeGesture)
Then, implement a function to handle the backNavigationFunction like below:
#objc func backNavigationFunction(_ sender: UIScreenEdgePanGestureRecognizer) {
let dX = sender.translation(in: view).x
if sender.state == .ended {
let fraction = abs(dX / view.bounds.width)
if fraction >= 0.35 {
//back navigation code here
}
}
}
Don't forget to make the ViewController inherit from the UIGestureRecognizerDelegate class (i.e. class WebViewController: UIViewController, WKUIDelegate, WKNavigationDelegate, UIGestureRecognizerDelegate). The delegate in question here is UIGestureRecognizerDelegate but I anticipate you'll need the others as well.