Fix deprecated methods in AppRTCMobile.

webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallViewController.m

Index: webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallViewController.m
diff --git a/webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallViewController.m b/webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallViewController.m
index d1ae3f94e05bb93c7f991441539b57f8be4a4448..cd42514a9f930690df6a97deb5e807427250b9ea 100644
--- a/webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallViewController.m
+++ b/webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallViewController.m
@@ -35,6 +35,8 @@
 }
 
 @synthesize videoCallView = _videoCallView;
+@synthesize localVideoTrack = _localVideoTrack;
+@synthesize remoteVideoTrack = _remoteVideoTrack;
 @synthesize delegate = _delegate;
 
 - (instancetype)initForRoom:(NSString *)room
@@ -214,12 +216,18 @@
 }
 
 - (void)showAlertWithMessage:(NSString*)message {
-  UIAlertView* alertView = [[UIAlertView alloc] initWithTitle:nil
-                                                      message:message
-                                                     delegate:nil
-                                            cancelButtonTitle:@"OK"
-                                            otherButtonTitles:nil];
-  [alertView show];
+  UIAlertController *alert =
+      [UIAlertController alertControllerWithTitle:nil
+                                          message:message
+                                   preferredStyle:UIAlertControllerStyleAlert];
+
+  UIAlertAction *defaultAction = [UIAlertAction actionWithTitle:@"OK"
+                                                          style:UIAlertActionStyleDefault
+                                                        handler:^(UIAlertAction *action){
+                                                        }];
+
+  [alert addAction:defaultAction];
+  [self presentViewController:alert animated:YES completion:nil];
 }
 
 @end