App intents are not supported

[Sroose]

Bug Report

Problem

Since changing to WKWebView (mandatory for IOS), apps do not get opened anymore (links with any custom app intent, say whatsapp:// etc)
The inappbrowser gives the error {"code":-1002,"message":"unsupported URL","type":"loaderror"}

What is expected to happen?

The app should open after clicking a link with their intent.

What does actually happen?

Nothing, an error is raised (unsupported URL)

Information

After opening (succesfully) a web page, this page holds buttons that open apps. These buttons dont work anymore.

Note: I am able to use this workaround to add the intent manually in a forked version of the in-app-browser.

I would prefer the solution to use the allowed intents from the cordova-plugin-queries-schemes plugin (or any intent)

Command or Code

const browserOptions = 'location=no,hardwareback=no,toolbar=yes';
const browser = this.iab.create(this.paymentUrl, '_blank', browserOptions);
const listener = browser.on('loadstart').subscribe((event: any) => {
  this.logger.debug('browser is opening url ' + event.url);` // log: browser is opening url intentname://bla
}
const errorListener = browser.on('loaderror').subscribe((event: any) => {
  this.logger.error('ERROR: ', event); // log: "ERROR: {"code":-1002,"message":"unsupported URL","type":"loaderror",...
}

### Environment, Platform, Device
IOS, cordova Ionic


### Version information
cordova-plugin-inappbrowser 4.0.0
<preference name="WKWebViewOnly" value="true" />

## Checklist
- [x] I searched for existing GitHub issues
- [x] I updated all Cordova tooling to most recent version
- [x] I included all the necessary information above

[fbrun]

Hi,
Same error under latest iOS 14, but with iOS 13, it's work

[fbrun]

I have make some tests with different custom schemes : one is open inside the inappbrowser view with a window.open, the other with a window.location.replace.

With the first nothing happen. The 'loadstart' event isn't detected too.
I see also that customscheme event is never used under ios, with cordova-plugin-inappbrowser@4.0.0. It's seem that the window.open in the web site displayed in the inapp web view not function, but i don't know why.

With the second, the event 'loadstart' is sended. As customscheme event is never used under ios, i can test the url to determine if it's a custom scheme in the loadstart event, then open it with iab.create(event.url, '_system') (iab is from '@ionic-native/in-app-browser'. It open successfully the app called.