How to get user details using twitter api v1.1 (Twitter error 215)

First, you need to Authenticate your request (Get permission).

second, see follow these steps:

1.Download FHSTwitterEngine Twitter Library.

2.Add the folder FHSTwitterEngine” to your project and #import "FHSTwitterEngine.h".

3.add SystemConfiguration.framework to your project.

Usage : 1.in the [ViewDidLoad] add the following code.

UIButton *logIn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    logIn.frame = CGRectMake(100, 100, 100, 100);
    [logIn setTitle:@"Login" forState:UIControlStateNormal];
    [logIn addTarget:self action:@selector(showLoginWindow:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:logIn];

[[FHSTwitterEngine sharedEngine]permanentlySetConsumerKey:@"<consumer_key>" andSecret:@"<consumer_secret>"];
    [[FHSTwitterEngine sharedEngine]setDelegate:self];

and don’t forget to import the delegate FHSTwitterEngineAccessTokenDelegate.

2. you need to get the permission for your request, with the following method which will present Login window:

- (void)showLoginWindow:(id)sender {
    [[FHSTwitterEngine sharedEngine]showOAuthLoginControllerFromViewController:self withCompletion:^(BOOL success) {
        NSLog(success?@"L0L success":@"O noes!!! Loggen faylur!!!");
    }];
}

when the Login window is presented, enter your Twitter Username and Password to authenticate your request.

3. add the following methods to your code:

-(void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [[FHSTwitterEngine sharedEngine]loadAccessToken];
    NSString *username = [[FHSTwitterEngine sharedEngine]loggedInUsername];// self.engine.loggedInUsername;
    if (username.length > 0) {
        lbl.text = [NSString stringWithFormat:@"Logged in as %@",username];
        [self listResults];


    } else {
        lbl.text = @"You are not logged in.";
    }

}
- (void)storeAccessToken:(NSString *)accessToken {
    [[NSUserDefaults standardUserDefaults]setObject:accessToken forKey:@"SavedAccessHTTPBody"];
}

- (NSString *)loadAccessToken {
    return [[NSUserDefaults standardUserDefaults]objectForKey:@"SavedAccessHTTPBody"];
}

4.Now you are ready to get your request, with the following method(in this method I created a Twitter search for some Hashtag, to get the screen_name for example):

- (void)listResults {

    dispatch_async(GCDBackgroundThread, ^{
        @autoreleasepool {
            [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

        // the following line contains a FHSTwitterEngine method wich do the search.

            dict = [[FHSTwitterEngine sharedEngine]searchTweetsWithQuery:@"#iOS" count:100 resultType:FHSTwitterEngineResultTypeRecent unil:nil sinceID:nil maxID:nil];
          // NSLog(@"%@",dict);
            NSArray *results = [dict objectForKey:@"statuses"];

          //  NSLog(@"array text = %@",results);
            for (NSDictionary *item in results) {
                NSLog(@"text == %@",[item objectForKey:@"text"]);
                NSLog(@"name == %@",[[item objectForKey:@"user"]objectForKey:@"name"]);
                NSLog(@"screen name == %@",[[item objectForKey:@"user"]objectForKey:@"screen_name"]);
                NSLog(@"pic == %@",[[item objectForKey:@"user"]objectForKey:@"profile_image_url_https"]);
            }

            dispatch_sync(GCDMainThread, ^{
                @autoreleasepool {
                    UIAlertView *av = [[UIAlertView alloc]initWithTitle:@"Complete!" message:@"Your list of followers has been fetched" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
                    [av show];
                    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
                }
            });
        }
    });
}

That’s all.
I just got the screen_name from a search Query, you can get a timeline for a user using the following methods:

// statuses/user_timeline
- (id)getTimelineForUser:(NSString *)user isID:(BOOL)isID count:(int)count;
- (id)getTimelineForUser:(NSString *)user isID:(BOOL)isID count:(int)count sinceID:(NSString *)sinceID maxID:(NSString *)maxID; 

instead of the search method above.

Note: see the FHSTwitterEngine.h to know what method you need to use.
Note: to get the <consumer_key> and the <consumer_secret> you need to to visit this link
to register your app in Twitter.