Catch Javascript Event in iOS WKWebview with Swift

Question

I am building an app with web programming languages and want to start the camera when the user clicks on an HTML button. Since I want my camera view to be a custom one, I need to design it with Swift. So when the user clicks on this HTML button, I want to "catch" this click in Swift so I can start my native camera view.

I know it can be done with the WKWebview, but I don't really know how to do that.

For example, my Javascript (jQuery) code could look like that :

// User clicks to start the native camera with Swift
$(".camera_button").click(function() {
    // Function to call the camera view from JS to Swift
});

Can you help me to do that?

Thanks.

Answer 1

Based on the answer from @Alex Pelletier, which really helped me, here is the solution the my question.

In my "loadView()" function, here is what I have :

let contentController = WKUserContentController();
contentController.addScriptMessageHandler(
    self,
    name: "callbackHandler"
)

let config = WKWebViewConfiguration()
config.userContentController = contentController

webView = WKWebView(frame: CGRectZero, configuration: config)
webView.navigationDelegate = self
view = webView

My function to handle the Javascript event which is sent to Swift :

func userContentController(userContentController: WKUserContentController, didReceiveScriptMessage message: WKScriptMessage)
    {
        if(message.name == "callbackHandler") {
            print("Launch my Native Camera")
        }
    }

... And finally, my Javascript (jQuery) code when a click happens on my camera button (in HTML) :

$(document).ready(function() {

    function callNativeApp () {
        try {
            webkit.messageHandlers.callbackHandler.postMessage("camera");
        } catch(err) {
            console.log('The native context does not exist yet');
        }
    }

    $(".menu-camera-icon").click(function() {
        callNativeApp();
    });
});

I hope it will help someone else :-) !