Xcode 4 iphone 3.1.3 applications not work

Question

i'm working with Xcode 4 and my software work well on iPhone 4 and simulator but when i test it on devices like iPhone 2G or 3Gs i have this error immediately when i run the code :

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[ setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key rootViewController.'

searching the way to solve the problem i build a hello world program and do not work on iPhone 3gs ... searching the solutions i found this :

// self.window.rootViewController = self.viewController; [self.window addSubview: [self.viewController view]];

use addsubview like this and the program should run fine ...

Ok the hello world run well but my program does not work at all ...

maybe this is the code i should change ... (but i don't now really ..)

 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {
// Override point for customization after application launch.

//this and application should run on 3.1.3
if ([self.window respondsToSelector:@selector(setRootViewController:)])
    self.window.rootViewController = self.viewController;
else
    [self.window addSubview:self.viewController.view];

// Add registration for remote notifications
[[UIApplication sharedApplication] 
 registerForRemoteNotificationTypes:(UIRemoteNotificationTypeAlert | UIRemoteNotificationTypeBadge | UIRemoteNotificationTypeSound)];

// Clear application badge when app launches
//application.applicationIconBadgeNumber = 0;

[self.window makeKeyAndVisible];

return YES;

}

i search some info about this problem but every time i search i found only to change the line self.window.rootViewController = self.viewController;

but unfortunately don't help much.

thanks guys for you're patience :)

EDIT :

i change the code

if ([self.window respondsToSelector:@selector(setRootViewController:)])
    self.window.rootViewController = self.viewController;
else
    [self.window addSubview:self.viewController.view];

to

[self.window addSubview:self.viewController.view];

but the error is still the same ...

Answer 1

UIWindow does not have a rootViewController property in iOS versions less than 4.0. Hence if you want to support these versions, you can't use self.window.rootViewController = myViewController;, you generally have to add the controller's view to the window, i.e.: [self.window addSubview:myViewController.view];

Edit: the problem is how you are checking for what version it is, since 3.1.3 could have still responded to setRootViewController (built in but not public variable).