Migrate flutter_view example to new plugin API (#9096)

Ref: flutter/engine#3539

examples/flutter_view/ios/Runner/MainViewController.m

diff --git a/examples/flutter_view/ios/Runner/MainViewController.m b/examples/flutter_view/ios/Runner/MainViewController.m
index 22819ac..8ff7b1f 100644
--- a/examples/flutter_view/ios/Runner/MainViewController.m
+++ b/examples/flutter_view/ios/Runner/MainViewController.m
@@ -35,9 +35,9 @@
   if ([segue.identifier isEqualToString:@"FlutterViewControllerSegue"]) {
     self.flutterViewController = segue.destinationViewController;
 
-    self.messageChannel = [FlutterMessageChannel messageChannelNamed:channel
-                                                     binaryMessenger:self.flutterViewController
-                                                               codec:[FlutterStringCodec sharedInstance]];
+    self.messageChannel = [FlutterMessageChannel messageChannelWithName:channel
+                                                        binaryMessenger:self.flutterViewController
+                                                                  codec:[FlutterStringCodec sharedInstance]];
 
     MainViewController*  __weak weakSelf = self;
     [self.messageChannel setMessageHandler:^(id message, FlutterReplyHandler replyHandler) {