feat(ios): Support custom scheme event for iOS (#1112)

- Add support for the `AllowedSchemes` preference and `customscheme` event for iOS like on Android.
- Token from PR #274 which was implementing it in `UIWebView`
- JIRA-Ticket: https://issues.apache.org/jira/browse/CB-14187

Author: kumo01GitHub

README.md

@@ -208,6 +208,7 @@ The object returned from a call to `cordova.InAppBrowser.open` when the target i
   - __exit__: event fires when the `InAppBrowser` window is closed.
   - __beforeload__: event fires when the `InAppBrowser` decides whether to load an URL or not (only with option `beforeload` set).
   - __message__: event fires when the `InAppBrowser` receives a message posted from the page loaded inside the `InAppBrowser` Webview.
+  - __customscheme__: event fires when a link is followed that matches `AllowedSchemes`.
   - __download__: _(Android Only)_ event fires when the `InAppBrowser` loads a URL that leads in downloading of a file.
 
 - __callback__: the function that executes when the event fires. The function is passed an `InAppBrowserEvent` object as a parameter.
@@ -309,6 +310,36 @@ function messageCallBack(params){
 }
 
 ```
+
+### Customscheme event Example
+
+Sometimes you may want to respond to an event happening on the page loaded in the browser,
+for example a button to open the barcode scanner, or closing the browser when a login flow
+was finished. This can done by navigating to a URL with a custom scheme listed in the
+`AllowedSchemes` preference in `config.xml`, triggering a `customscheme` event on the
+browser. Multiple values are separated by comma's.
+
+- **type** _it contains the String value "customscheme" always_
+- **url** _The url with custom scheme that triggered the event_
+
+In `config.xml`, include the following:
+```xml
+<preference name="AllowedSchemes" value="app" />
+```
+
+```javascript
+function onCustomScheme(e) {
+  if (e.url === 'app://hide') {
+    inAppBrowserRef.hide();
+  }
+}
+
+inAppBrowserRef = cordova.InAppBrowser.open('https://example.com', '_blank');
+inAppBrowserRef.addEventListener('customscheme', onCustomScheme);
+```
+
+When the opened page navigates to the link `app://hide`, the browser is hidden.
+
 #### Download event Example
 
 Whenever the InAppBrowser receives or locates to a url which leads in downloading a file, the callback assigned to the "download" event is called. The parameter passed to this callback is an object with the the following properties
@@ -340,7 +371,7 @@ function downloadListener(params){
 
 ### InAppBrowserEvent Properties
 
-- __type__: the eventname, either `loadstart`, `loadstop`, `loaderror`, `message` or `exit`. _(String)_
+- __type__: the eventname, either `loadstart`, `loadstop`, `loaderror`, `message`, `customscheme` or `exit`. _(String)_
 - __url__: the URL that was loaded. _(String)_
 - __code__: the error code, only in the case of `loaderror`. _(Number)_
 - __message__: the error message, only in the case of `loaderror`. _(String)_
@@ -354,7 +385,7 @@ function downloadListener(params){
 
 ### Browser Quirks
 
-`loadstart`, `loaderror`, `message` events are not fired.
+`loadstart`, `loaderror`, `message`, `customscheme` events are not fired.
 
 ### Quick Example
 
@@ -376,6 +407,7 @@ function downloadListener(params){
   - __loaderror__: event fires when the `InAppBrowser` encounters an error loading a URL.
   - __exit__: event fires when the `InAppBrowser` window is closed.
   - __message__: event fires when the `InAppBrowser` receives a message posted from the page loaded inside the `InAppBrowser` Webview.
+  - __customscheme__: event fires when a link is followed that matches `AllowedSchemes`.
   - __download__: _(Android only)_ event fires when the `InAppBrowser` loads a URL that leads in downloading of a file.
 
 - __callback__: the function to execute when the event fires.

src/ios/CDVWKInAppBrowser.m

@@ -413,6 +413,21 @@ - (void)injectStyleFile:(CDVInvokedUrlCommand *)command
     [self injectDeferredObject:[command argumentAtIndex:0] withWrapper:jsWrapper];
 }
 
+- (BOOL)isAllowedScheme:(NSString *)scheme
+{
+    NSString *allowedSchemesPreference = [self.commandDelegate.settings cordovaSettingForKey:@"AllowedSchemes"];
+    if (allowedSchemesPreference == nil || [allowedSchemesPreference isEqualToString:@""]) {
+        // Preference missing.
+        return NO;
+    }
+    for (NSString *allowedScheme in [allowedSchemesPreference componentsSeparatedByString:@","]) {
+        if ([allowedScheme isEqualToString:scheme]) {
+            return YES;
+        }
+    }
+    return NO;
+}
+
 /**
  * The message handler bridge provided for the InAppBrowser is capable of executing any oustanding callback belonging
  * to the InAppBrowser plugin. Care has been taken that other callbacks cannot be triggered, and that no
@@ -465,6 +480,15 @@ - (void)webView:(WKWebView *)theWebView decidePolicyForNavigationAction:(WKNavig
     if ([allowedSchemes containsObject:[url scheme]]) {
         [theWebView stopLoading];
         [self openInSystem:url];
+        shouldStart = NO;
+    } else if ((self.callbackId != nil) && ![[url scheme] isEqualToString:@"http"] && ![[url scheme] isEqualToString:@"https"] && [self isAllowedScheme:[url scheme]]) {
+        // Send a customscheme event for allowed schemes that are not http/https.
+        CDVPluginResult *pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_OK
+                                                      messageAsDictionary:@{@"type":@"customscheme", @"url":[url absoluteString]}];
+        [pluginResult setKeepCallback:[NSNumber numberWithBool:YES]];
+        
+        [self.commandDelegate sendPluginResult:pluginResult callbackId:self.callbackId];
+        
         shouldStart = NO;
     } else if ((self.callbackId != nil) && isTopLevelNavigation) {
         // Send a loadstart event for each top-level navigation (includes redirects).

tests/tests.js

@@ -377,6 +377,7 @@ exports.defineManualTests = function (contentEl, createActionButton) {
         'Make sure http://www.apple.com is not in the white list.</br>' +
         'In iOS, starred <span style="vertical-align:super">*</span> tests will put the app in a state with no way to return. </br>' +
         '<h4>User-Agent: <span id="user-agent"> </span></hr>' +
+        'Make sure your config.xml contains: &lt;preference name="AllowedSchemes" value="custom" &gt;/<br/>' +
         '</div>';
 
     const local_tests =
@@ -525,6 +526,11 @@ exports.defineManualTests = function (contentEl, createActionButton) {
         '<p/> <div id="openHardwareBackDefaultAfterNo"></div>' +
         'Expected result: consistently open browsers with with the appropriate option: hardwareback=defaults to yes then hardwareback=no then hardwareback=defaults to yes. By default hardwareback is yes so pressing back button should navigate backwards in history then close InAppBrowser';
 
+    const customscheme_tests =
+        '<h1>Customscheme</h1>' +
+        '<p/> <div id="openCustomscheme"></div>' +
+        'Expected result: open an alert dialog with the text "Results verified". Works only on Android and iOS.';
+
     contentEl.innerHTML =
         info_div +
         platform_info +
@@ -539,7 +545,8 @@ exports.defineManualTests = function (contentEl, createActionButton) {
         clearing_cache_tests +
         video_tag_tests +
         local_with_anchor_tag_tests +
-        hardwareback_tests;
+        hardwareback_tests +
+        customscheme_tests;
 
     document.getElementById('user-agent').textContent = navigator.userAgent;
 
@@ -979,4 +986,28 @@ exports.defineManualTests = function (contentEl, createActionButton) {
         },
         'openHardwareBackDefaultAfterNo'
     );
+
+    // Customscheme
+    createActionButton(
+        'customscheme',
+        function () {
+            const ref = cordova.InAppBrowser.open('about:blank', '_blank', 'hidden=yes' + (platformOpts ? ',' + platformOpts : ''));
+            ref.addEventListener('loadstop', function (_) {
+                ref.executeScript({ code: 'window.location.replace("custom://test");' });
+            });
+            ref.addEventListener('customscheme', function (e) {
+                if (e && e.url === 'custom://test') {
+                    alert('Results verified');
+                } else {
+                    alert('Got: ' + e.url);
+                }
+                ref.close();
+            });
+            ref.addEventListener('loaderror', function (e) {
+                alert('Load error: ' + e.message + '\nYou may need to set the AllowedSchemes preference');
+                ref.close();
+            });
+        },
+        'openCustomscheme'
+    );
 };