Question

So I am writing an app that will read a JSON feed. In my application:didFinishLaunchingWithOptions, I am writing some code to download the JSON string and store it into a local NSString variable. I will then pass that string into ListingsViewController (which is the Root VC of the NavigationController). When I print out the JSON data in ListingsViewController, it is showing me (null) which is making me think that viewDidLoad is loading before – which seems illogical?

So here is my application:didFinishLaunchingWithOptions

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

    // Grab the feeds    
    NSURL *jsonURL = [NSURL URLWithString:@"http://www.shoofeetv.com/iphonexml/view/all_channels.json"];
    NSString *jsonData = [[NSString alloc] initWithContentsOfURL:jsonURL];

    // Pass jsonData to the ListingsViewController
    ListingsViewController *listingsViewController = [[ListingsViewController alloc] initWithNibName:@"ListingsViewController" bundle:nil];
    listingsViewController.jsonData = jsonData;
    [listingsViewController release];

    // Display the navigation controller
    self.window.rootViewController = self.navigationController;
    [self.window makeKeyAndVisible];

    return YES;
}

My viewDidLoad method is as follows:

- (void)viewDidLoad {

    self.navigationItem.title = @"Listings";
    UIBarButtonItem *checkinButton = [[UIBarButtonItem alloc]
                                  initWithTitle:@"Check In" 
                                  style:UIBarButtonItemStylePlain
                                  target:self
                                  action:@selector(switchView)];

    self.navigationItem.rightBarButtonItem = checkinButton;
    [checkinButton release];

   NSLog(@"%@", self.jsonData);

   [super viewDidLoad];
}

Please note that a common solution is to make sure that the App Delegate in MainWindow.xib must be connected to the File’s Owner. Mine already is connected.

I will appreciate any help!

Thank you everyone.

Answer 1

well you are setting up a view controller with your code, but it is never shown within the navigation controller. you just set up a view controller, assign its jsonData a string and destroy the view controller immediately. I#m pretty sure the output you get is from a different view controller that you create in your main XIB.

what you want to do is create an empty navigation controller in your XIB and then do the following:

// Pass jsonData to the ListingsViewController
ListingsViewController *listingsViewController = [[ListingsViewController alloc] initWithNibName:@"ListingsViewController" bundle:nil];
listingsViewController.jsonData = jsonData;
[self.navigationController pushViewController:listingsViewController animated:NO];
[listingsViewController release];

// Display the navigation controller
self.window.rootViewController = self.navigationController;
[self.window makeKeyAndVisible];

this will actually display the view controller you created.

Also remember that when you deploy your application, you need to load your json-data asynchronously and handle network errors (apple will test your app under various network conditions)