Merge pull request #56 from lane128/fix_issue_55

fix issue 55

ios/Classes/FluttertoastPlugin.m

@@ -38,7 +38,7 @@ static NSString *const CHANNEL_NAME = @"PonnamKarthik/fluttertoast";
 - (void)handleMethodCall:(FlutterMethodCall *)call result:(FlutterResult)result {
     if([@"cancel" isEqualToString:call.method]) {
         [[UIApplication sharedApplication].delegate.window.rootViewController.view hideAllToasts];
-        result(true);
+        result([NSNumber numberWithBool:true]);
     } else if ([@"showToast" isEqualToString:call.method]) {
         NSString *msg = call.arguments[@"msg"];
         NSString *gravity = call.arguments[@"gravity"];
@@ -84,7 +84,7 @@ static NSString *const CHANNEL_NAME = @"PonnamKarthik/fluttertoast";
                                                                                            style:style
                                                                                            ];
         }
-        result(true);
+        result([NSNumber numberWithBool:true]);
 
     } else {
         result(FlutterMethodNotImplemented);