[RN] Fix opening the same URL multiple times

Deep/universal linking now utilizes loadURL (when possible). But loadURL
is imperative in the native source code while its JavaScript counterpart
i.e. React App Component prop url is declarative. So there's the
following bug: open a URL, leave the conference (by tapping the hangup
button, for example), and then opening the same URL actually leaves you
on the Welcome page (if enabled; otherwise, a black screen).

The implementation has a flow though: opening the same URL twice in a
row without an intervening leave will leave the first opening and join
the new opening. Which can be improved by not leaving and joining if the
conference is joined, joining, an not leaving. But that can be done
separately as an improvement independent of the current implementation
details.

ios/sdk/src/JitsiMeetView.m

@@ -15,6 +15,7 @@
  */
 
 #import <CoreText/CoreText.h>
+#include <mach/mach_time.h>
 
 #import <React/RCTAssert.h>
 #import <React/RCTLinkingManager.h>
@@ -239,6 +240,17 @@ static NSMapTable<NSString *, JitsiMeetView *> *views;
         props[@"url"] = urlObject;
     }
 
+    // XXX The method loadURLObject: is supposed to be imperative i.e. a second
+    // invocation with one and the same URL is expected to join the respective
+    // conference again if the first invocation was followed by leaving the
+    // conference. However, React and, respectively,
+    // appProperties/initialProperties are declarative expressions i.e. one and
+    // the same URL will not trigger componentWillReceiveProps in the JavaScript
+    // source code. The workaround implemented bellow introduces imperativeness
+    // in React Component props by defining a unique value per loadURLObject:
+    // invocation.
+    props[@"timestamp"] = @(mach_absolute_time());
+
     if (rootView) {
         // Update props with the new URL.
         rootView.appProperties = props;

react/features/app/components/AbstractApp.js

@@ -47,6 +47,10 @@ export class AbstractApp extends Component {
          */
         store: PropTypes.object,
 
+        // XXX Refer to the implementation of loadURLObject: in
+        // ios/sdk/src/JitsiMeetView.m for further information.
+        timestamp: PropTypes.any,
+
         /**
          * The URL, if any, with which the app was launched.
          */
@@ -143,7 +147,11 @@ export class AbstractApp extends Component {
         let { url } = nextProps;
 
         url = toURLString(url);
-        if (toURLString(this.props.url) !== url) {
+        if (toURLString(this.props.url) !== url
+
+                // XXX Refer to the implementation of loadURLObject: in
+                // ios/sdk/src/JitsiMeetView.m for further information.
+                || this.props.timestamp !== nextProps.timestamp) {
             this._openURL(url || this._getDefaultURL());
         }
     }