在iPhone应用程序中显示Facebook朋友列表

Question

I am making an IPhone application in which I connect the Facebook.I am connecting it on button click of my first view controller.Now I add second button and open second view controller in this I want to show the list of my friends in alphabetical order.I search it on net but when I applied it in my application ,it crash on run time please help me-

in my delegate class

 (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    // Override point for customization after application launch.
    self.viewController = [[[ViewController alloc] initWithNibName:@"ViewController" bundle:nil] autorelease];
    navController =[[UINavigationController alloc] initWithRootViewController:self.viewController];

    self.window.rootViewController = navController;

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    if ([defaults objectForKey:@"FBAccessTokenKey"] 
        && [defaults objectForKey:@"FBExpirationDateKey"]) {
        facebook.accessToken = [defaults objectForKey:@"FBAccessTokenKey"];
        facebook.expirationDate = [defaults objectForKey:@"FBExpirationDateKey"];
    }            
    [self.window makeKeyAndVisible];
    return YES;
}

-(void)fbDidLogin
{
    NSUserDefaults *defaults=[NSUserDefaults standardUserDefaults];        
    [defaults setObject:[facebook accessToken] forKey:@"FBAccessTokenKey"];        
    [defaults setObject:[facebook expirationDate] forKey:@"FBExpirationDateKey"];              
}

My second view controller in which I want to show the list of my friends in loading

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.        
    NSArray   *_permissions = [[NSArray arrayWithObjects:@"read_stream", @"publish_stream", @"offline_access",@"read_friendlists",nil] retain];        
    [facebook authorize:_permissions];        
    facebook = [[Facebook alloc] initWithAppId:@"APP_ID_HERE" andDelegate:self];        
    [facebook requestWithGraphPath:@"me" andDelegate:self];
    [facebook requestWithGraphPath:@"me/friends" andDelegate:self];
  //  NSMutableDictionary*params = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"4",@"uids", @"name", @"fields", nil];
    [facebook requestWithGraphPath:@"me/friends" 
                         andParams:[ NSDictionary dictionaryWithObjectsAndKeys:@"picture,id,name,link,gender,last_name,first_name",@"fields",nil]
                       andDelegate:self];        
}

Any help is appreciated.

Answer 1

Issue #1: This line:

facebook = [[Facebook alloc] initWithAppId:@"XXXXXXXXXXXXX" andDelegate:self];

needs to be in your app delegate in didFinishLaunchingWithOptions before you try and read NSUserDefaults and access the Facebook object that has not been initialized yet. It should also be removed from your view controller.

Issue #2: It appears you have a facebook variable declared in both your app delegate and your view controller. You should only have one Facebook instance in your whole application. When you are calling it from your view controller you should do something like this to get a reference to the Facebook instance stored at your app delegate:

Facebook *facebook = ((MyAppDelegate *)[[UIApplication sharedApplication] delegate]).facebook;

You also need to make sure you implemented the openURL method in your app delegate and followed the setup instructions to create the URL scheme in your plist file.

ps. You shouldn't post your AppId onto a public forum.