How to fix "property implementation must have its declaration in interface 'Appdelegate'" - objective-c

Question

//
// AppDelegate.m
// Foody
//
// Created by Iceeiei on 5/2/15.
// Copyright (c) 2015 pondandfriend. All rights reserved.
//
#import "AppDelegate.h"
#import "ViewController.h"
#import "RecipeList.h"
#interface AppDelegate ()
#end
#implementation AppDelegate
#synthesize window = _window;
#synthesize viewController = _viewController;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.viewController = [[ViewController alloc]initWithNibName:#"ViewController" bundle:nil];
RecipeList *recipeList = [[RecipeList alloc] initWithNibName:#"RecipeList" bundle:nil];
self.window.rootViewController = recipeList;
[self.window makeKeyAndVisible];
return YES;
}
- (void)applicationWillResignActive:(UIApplication *)application {
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}
- (void)applicationDidEnterBackground:(UIApplication *)application {
}
- (void)applicationWillEnterForeground:(UIApplication *)application {
}
- (void)applicationDidBecomeActive:(UIApplication *)application {
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
- (void)applicationWillTerminate:(UIApplication *)application {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}
#end
Error 1:
property implementation must have its declaration in interface 'Appdelegate'
Error 2:
Property'viewController' not found on object of type 'AppDelegate'
Is there any way to fix this?

Answer 1

It looks like you haven't added the #property notation for your ViewController in the .h. Add the following to AppDelegate.h:
#propery (nonatomic) ViewController *viewController;