JavaScriptInterface

UIWebview extension help you to call native code from Javascript in the iOS application. And call Javascript function from iOS Application.

Support Swift 4.0. It's similar WebView.addJavascriptInterface in the Android application.

Setting your project

Step 1: Expand the Link Binary With Libraries section and add the following item: JavaScriptCore.framework

Step 2:

• Define a protocol, inherit from JSExport protocol, which contains these native functions as you want to work with JavaScript. For example:

@objc protocol MyExport : JSExport
{
    func check(_ message : String)
    func sayGreeting(_ message: String, _ name: String)
    func anotherSayGreeting(_ message: String, name: String)
    func showDialog(_ title: String, _ message : String)
}

Step 3: Define a class to implement native functions above.

class JSInterface : NSObject, MyExport
{
    func check(_ message: String) {
        print("JS Interface works!")
    }
    
    func sayGreeting(_ message: String, _ name: String)
    {
        print("sayGreeting: \(message): \(name)")
    }
    
    func anotherSayGreeting(_ message: String, name: String)
    {
        print("anotherSayGreeting: \(message): \(name)")
    }

    func showDialog(_ title: String, _ message : String)
    {
        dispatch_async(dispatch_get_main_queue(), {
            UIAlertView(title: title, message: message, delegate: nil, cancelButtonTitle: "OK").show()
        })
    }
}

Step 4: Create an outlet to the webview in your view controller

@IBOutlet weak var webView : UIWebView!

Step 5: Add java script interface as below at viewDidLoad:

self.webView.addJavascriptInterface(JSInterface(), forKey: "Native");

Usage

Now to call those native functions above from JavaScipt is loaded your webview, just call:

Native.check()

Native.sayGreeting('Hello', 'JavaScript Interface')

Define a function showAlert in Javascript

<script>
    function showAlert(agr1, agr2){
        alert('agr1: ' + agr1 + ' - agr2: ' + agr2);
        return 'return from javascript';
    }
</script>

Now you can call Javascript function from iOS Application, from ViewController

let result = self.webView.callJSMethod(name: "showAlert", agruments: "Sua", "80.51")
        
print("result: \(result ?? "no return value")")

Avoid memmory leak, at deinit of ViewController:

deinit {
        self.webView.removeJavascriptInterfaces()
    }