Question

I’m trying to make some sort of setup wizard that remembers a specific view however I have some problems with my AppDelegate.m code since I’m using ARC.
Does anyone know how to fix this, because If I compile the app crashes at the splash screen..

My AppDelegate.m:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{

    NSString *controllerName = [[NSUserDefaults standardUserDefaults] objectForKey:@"WIZARD_VIEW"];
    if ([controllerName length]) {
        Class controllerClass = NSClassFromString(controllerName);
        UIViewController *controller = [[controllerClass alloc] init];

    // Override point for customization after application launch.
    return YES;
    }

To be more clear, in the viewcontroller files I added the following code as a suggestion:

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [[NSUserDefaults standardUserDefaults] setObject:[[self class] description] forKey:@"WIZARD_VIEW"];
     NSLog(@"ViewWillAppear Done.");
    [[NSUserDefaults standardUserDefaults] synchronize];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [[NSUserDefaults standardUserDefaults] removeObjectForKey:@"WIZARD_VIEW"];
     NSLog(@"viewWillDisappear");
    [[NSUserDefaults standardUserDefaults] synchronize];
}

Crashlog while compiling:

/Users/Tim/Documents/XCODE_DEV/App/AppDelegate.m:17:33: No visible @interface for 'NSUserDefaults' declares the selector 'forKey:'

/Users/Tim/Documents/XCODE_DEV/App/AppDelegate.m:20:27: Unused variable 'controller'

Answer 1

The first time you have to register the defaults.To register the defaults isn’t enough to call the setObject:forKey method, you have to use the registerDefaults method:

- (void)registerDefaults:(NSDictionary *)dictionary;

Documentation:
NSUserDefaults

So in your case:

NSUserDefaults* standard=[NSUserDefaults standardUserDefaults];
[standard registerDefaults: @{ @"WIZARD_VIEW" : [[self class]description]} ];

You better place these lines in the initialize method, which gets called before any non-static method.If the defaults are already registred there’s no problem, this will not overwrite the defaults that you have if is the 2nd+ time that the application starts.