title: unknown type name in objective c
body: <p>I'm pretty new to objective c, and having some basic problems.</p>
  
  <p>I wrote a simple program using a navigator, and everything worked fine.
  then I added few lines of code (can't even remember what exactly, and it seems to have no connection to the problem) and the problem occurred. I tried ctrl+z, and the problem remained:</p>
  
  <p>I run the program and get these errors:</p>
  
  <pre><code>1. unknown type name "mainController"
  2. property with 'retain (or strong)' attribute must be of object type
  </code></pre>
  
  <p>while mainController is the first screen to be loaded.</p>
  
  <p>This is the appDelegate.h file:</p>
  
  <pre><code>#import &lt;UIKit/UIKit.h&gt;
  #import "mainController.h"
  #import "WishesList.h"
  #import "Wish.h"
  
  @interface AppDelegate : UIResponder &lt;UIApplicationDelegate&gt;
  
  @property (strong, nonatomic) UIWindow *window;
  @property (strong, nonatomic) IBOutlet UINavigationController *navController;
  @property (strong, nonatomic) IBOutlet mainController *viewController; // this line creates the errors
  @property (strong, nonatomic) WishesList *WishesArray;
  @property (strong, nonatomic) NSIndexPath *temp;
  
  @end
  </code></pre>
  
  <p>this is the relevant part of the appDelegate.m file:</p>
  
  <pre><code>- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:    (NSDictionary *)launchOptions
  {
      self.window = [[UIWindow alloc]initWithFrame:[[UIScreen mainScreen]bounds]];
      WishesArray = [[WishesList alloc]init];
      temp = nil;
      [self setViewController:[[mainController alloc]init]];
      [self setNavController:[[UINavigationController alloc]initWithRootViewController:self.viewController]];
      [self.window setRootViewController:navController];
      [self.window makeKeyAndVisible];
      return YES;
  }
  </code></pre>
  
  <p>And this is mainController.h:</p>
  
  <pre><code>#import &lt;UIKit/UIKit.h&gt;
  #import "addWishController.h"
  #import "displayWish.h"
  #import "WishesList.h"
  #import "Wish.h"
  
  @interface mainController : UIViewController
  
  @property (nonatomic, weak) WishesList *list;
  @property (nonatomic, strong) IBOutlet UITableView *wishTable;
  
  - (void)addWish;
  
  @end
  </code></pre>
  
  <p>it already worked...<br />
  can you figure it out?</p>
  
  <p>thanks</p>