JavaScript to Swift communication

Question

Hey guys,

Programming environemnt :

swift version : 4.0

xcode version : 9.2

My objective :

1- Open a web application in ios and

2 - Communicate with its elements using JavaScript - invoke a method in my native app

what I have done so far :

I can load my application using webkit view.

challenges :

I found few old instructions for invoking native code from web applications JS functions which sadly won't work in newer versions of swift. due to swift upgrade.

function/methods like : NSBundle that are no longer available.

Main Question :

how can I invoke a method in native app from JavaScript

Thank you

Swift

5.5k

Posted by

john217

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Answer 1

how can I invoke a method in native app from JavaScript

That depends on what type of web view you’re using. The recommended web view for this sort of thing is

WKWebView

. In that view you can invoke native methods from JavaScript via the

WKScriptMessage

mechanism:

When you create the web view, you have to pass in a
```
WKWebViewConfiguration
```
. Add yourself as a script message handler for the message in question:
```
webViewConfiguration.userContentController.add(self, name: "myMessageName")
```
.

In JavaScript, send a message with code like this:

window.webkit.messageHandlers.myMessageName.postMessage(message)

.

Back in native, this will call the script message handler method that you registered:

func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
    assert(message.name == "myMessageName")
    … handle the message …
}

.

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Posted by

eskimo

Hi this is excellent and worked perfectly for what I need.

Does anyone know how I can do this the other way? So from Swift to Javascript?

Thanks,

Chris

—
Chardie
you can use webView.evaluateJavaScript or WKUserContentController to add user script.

—
Steven Tran

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JavaScript to Swift communication

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